cfg80211: remove enum ieee80211_band

This enum is already perfectly aliased to enum nl80211_band, and
the only reason for it is that we get IEEE80211_NUM_BANDS out of
it. There's no really good reason to not declare the number of
bands in nl80211 though, so do that and remove the cfg80211 one.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/realtek/rtlwifi/wifi.h

@@ -1359,7 +1359,7 @@ struct rtl_mac {
 	u32 tx_ss_num;
 	u32 rx_ss_num;
 
-	struct ieee80211_supported_band bands[IEEE80211_NUM_BANDS];
+	struct ieee80211_supported_band bands[NUM_NL80211_BANDS];
 	struct ieee80211_hw *hw;
 	struct ieee80211_vif *vif;
 	enum nl80211_iftype opmode;