Since Linux 4.7, the enum ieee80211_band is no longer used

This shall cause no problem's since both enums ieee80211_band
and nl80211_band were added in the same commit:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit?id=13ae75b103e07304a34ab40c9136e9f53e06475c

This patch refactors the references of IEEE80211_BAND_* to NL80211_BAND_*

Reference:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit?id=57fbcce37be7c1d2622b56587c10ade00e96afa3

This patch is based on
https://github.com/archlinuxcn/repo/tree/f4d6cff1cacf8dad13006fade5f96bc2cf020a9b/broadcom-wl-dkms .

Index: broadcom-sta/amd64/src/wl/sys/wl_cfg80211_hybrid.c
===================================================================
--- broadcom-sta.orig/amd64/src/wl/sys/wl_cfg80211_hybrid.c
+++ broadcom-sta/amd64/src/wl/sys/wl_cfg80211_hybrid.c
@@ -236,7 +236,7 @@ static s8 wl_dbg_estr[][WL_DBG_ESTR_MAX]
 #endif				
 
 #define CHAN2G(_channel, _freq, _flags) {			\
-	.band			= IEEE80211_BAND_2GHZ,		\
+	.band			= NL80211_BAND_2GHZ,		\
 	.center_freq		= (_freq),			\
 	.hw_value		= (_channel),			\
 	.flags			= (_flags),			\
@@ -245,7 +245,7 @@ static s8 wl_dbg_estr[][WL_DBG_ESTR_MAX]
 }
 
 #define CHAN5G(_channel, _flags) {				\
-	.band			= IEEE80211_BAND_5GHZ,		\
+	.band			= NL80211_BAND_5GHZ,		\
 	.center_freq		= 5000 + (5 * (_channel)),	\
 	.hw_value		= (_channel),			\
 	.flags			= (_flags),			\
@@ -379,7 +379,7 @@ static struct ieee80211_channel __wl_5gh
 };
 
 static struct ieee80211_supported_band __wl_band_2ghz = {
-	.band = IEEE80211_BAND_2GHZ,
+	.band = NL80211_BAND_2GHZ,
 	.channels = __wl_2ghz_channels,
 	.n_channels = ARRAY_SIZE(__wl_2ghz_channels),
 	.bitrates = wl_g_rates,
@@ -387,7 +387,7 @@ static struct ieee80211_supported_band _
 };
 
 static struct ieee80211_supported_band __wl_band_5ghz_a = {
-	.band = IEEE80211_BAND_5GHZ,
+	.band = NL80211_BAND_5GHZ,
 	.channels = __wl_5ghz_a_channels,
 	.n_channels = ARRAY_SIZE(__wl_5ghz_a_channels),
 	.bitrates = wl_a_rates,
@@ -395,7 +395,7 @@ static struct ieee80211_supported_band _
 };
 
 static struct ieee80211_supported_band __wl_band_5ghz_n = {
-	.band = IEEE80211_BAND_5GHZ,
+	.band = NL80211_BAND_5GHZ,
 	.channels = __wl_5ghz_n_channels,
 	.n_channels = ARRAY_SIZE(__wl_5ghz_n_channels),
 	.bitrates = wl_a_rates,
@@ -1876,8 +1876,8 @@ static s32 wl_alloc_wdev(struct device *
 	wdev->wiphy->max_num_pmkids = WL_NUM_PMKIDS_MAX;
 #endif
 	wdev->wiphy->interface_modes = BIT(NL80211_IFTYPE_STATION) | BIT(NL80211_IFTYPE_ADHOC);
-	wdev->wiphy->bands[IEEE80211_BAND_2GHZ] = &__wl_band_2ghz;
-	wdev->wiphy->bands[IEEE80211_BAND_5GHZ] = &__wl_band_5ghz_a; 
+	wdev->wiphy->bands[NL80211_BAND_2GHZ] = &__wl_band_2ghz;
+	wdev->wiphy->bands[NL80211_BAND_5GHZ] = &__wl_band_5ghz_a; 
 	wdev->wiphy->signal_type = CFG80211_SIGNAL_TYPE_MBM;
 	wdev->wiphy->cipher_suites = __wl_cipher_suites;
 	wdev->wiphy->n_cipher_suites = ARRAY_SIZE(__wl_cipher_suites);
@@ -2000,7 +2000,7 @@ static s32 wl_inform_single_bss(struct w
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 39)
 	freq = ieee80211_channel_to_frequency(notif_bss_info->channel,
 		(notif_bss_info->channel <= CH_MAX_2G_CHANNEL) ?
-		IEEE80211_BAND_2GHZ : IEEE80211_BAND_5GHZ);
+		NL80211_BAND_2GHZ : NL80211_BAND_5GHZ);
 #else
 	freq = ieee80211_channel_to_frequency(notif_bss_info->channel);
 #endif
@@ -2116,7 +2116,7 @@ wl_notify_connect_status(struct wl_cfg80
 				return err;
 			}
 			chan = wf_chspec_ctlchan(chanspec);
-			band = (chan <= CH_MAX_2G_CHANNEL) ? IEEE80211_BAND_2GHZ : IEEE80211_BAND_5GHZ;
+			band = (chan <= CH_MAX_2G_CHANNEL) ? NL80211_BAND_2GHZ : NL80211_BAND_5GHZ;
 			freq = ieee80211_channel_to_frequency(chan, band);
 			channel = ieee80211_get_channel(wiphy, freq);
 			cfg80211_ibss_joined(ndev, (u8 *)&wl->bssid, channel, GFP_KERNEL);
@@ -2250,10 +2250,10 @@ static void wl_ch_to_chanspec(struct iee
 		join_params->params.chanspec_list[0] =
 		    ieee80211_frequency_to_channel(chan->center_freq);
 
-		if (chan->band == IEEE80211_BAND_2GHZ) {
+		if ( (int) chan->band == (int) NL80211_BAND_2GHZ) {
 			chanspec |= WL_CHANSPEC_BAND_2G;
 		}
-		else if (chan->band == IEEE80211_BAND_5GHZ) {
+		else if ( (int) chan->band == (int) NL80211_BAND_5GHZ) {
 			chanspec |= WL_CHANSPEC_BAND_5G;
 		}
 		else {
@@ -2885,7 +2885,7 @@ static s32 wl_update_wiphybands(struct w
 
 	if (phy == 'n' || phy == 'a' || phy == 'v') {
 		wiphy = wl_to_wiphy(wl);
-		wiphy->bands[IEEE80211_BAND_5GHZ] = &__wl_band_5ghz_n;
+		wiphy->bands[NL80211_BAND_5GHZ] = &__wl_band_5ghz_n;
 	}
 
 	return err;