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>

include/uapi/linux/nl80211.h

@@ -3653,11 +3653,15 @@ enum nl80211_txrate_gi {
  * @NL80211_BAND_2GHZ: 2.4 GHz ISM band
  * @NL80211_BAND_5GHZ: around 5 GHz band (4.9 - 5.7 GHz)
  * @NL80211_BAND_60GHZ: around 60 GHz band (58.32 - 64.80 GHz)
+ * @NUM_NL80211_BANDS: number of bands, avoid using this in userspace
+ *	since newer kernel versions may support more bands
  */
 enum nl80211_band {
 	NL80211_BAND_2GHZ,
 	NL80211_BAND_5GHZ,
 	NL80211_BAND_60GHZ,
+
+	NUM_NL80211_BANDS,
 };
 
 /**