cfg80211: make nl80211_send_mlme_timeout() static

Fixes sparse complaint:

  CHECK   net/wireless/nl80211.c
net/wireless/nl80211.c:3694:6:
	warning: symbol 'nl80211_send_mlme_timeout'
	was not declared. Should it be static?
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/wireless/nl80211.c

@@ -3696,7 +3696,7 @@ void nl80211_send_disassoc(struct cfg80211_registered_device *rdev,
 				NL80211_CMD_DISASSOCIATE);
 }
 
-void nl80211_send_mlme_timeout(struct cfg80211_registered_device *rdev,
+static void nl80211_send_mlme_timeout(struct cfg80211_registered_device *rdev,
 				      struct net_device *netdev, int cmd,
 				      const u8 *addr)
 {