mac80211: Remove unused 'sband' and 'local' variables

Commit b1bce14a79 (mac80211: update opmode when adding new station)
refactored ieee80211_vht_handle_opmode into __ieee80211_vht_handle_opmode
and ieee80211_vht_handle_opmode leaving a set but unused variable
(sband) in the former. Compiling with W=1 gives the following warning,
fix it.

net/mac80211/vht.c: In function ‘__ieee80211_vht_handle_opmode’:
net/mac80211/vht.c:424:35: warning: variable ‘sband’ set but not used [-Wunused-but-set-variable]

Remove 'struct ieee80211_local* local' as well, it was only used to
set sband.

This is a harmless warning, and is only being fixed to reduce the
noise with W=1 in the kernel.

Fixes: b1bce14a79 ("mac80211: update opmode when adding new station")
Cc: Marek Kwaczynski <marek.kwaczynski@tieto.com>
Cc: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Kirtika Ruchandani <kirtika@chromium.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/vht.c

@@ -436,14 +436,10 @@ u32 __ieee80211_vht_handle_opmode(struct ieee80211_sub_if_data *sdata,
 				  struct sta_info *sta, u8 opmode,
 				  enum nl80211_band band)
 {
-	struct ieee80211_local *local = sdata->local;
-	struct ieee80211_supported_band *sband;
 	enum ieee80211_sta_rx_bandwidth new_bw;
 	u32 changed = 0;
 	u8 nss;
 
-	sband = local->hw.wiphy->bands[band];
-
 	/* ignore - no support for BF yet */
 	if (opmode & IEEE80211_OPMODE_NOTIF_RX_NSS_TYPE_BF)
 		return 0;