cfg80211: move cfg80211_exit to .exit.text

cfg80211_exit is only used as module_exit function, so it can go to
.exit.text saving a few bytes when CONFIG_CFG80211=y.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/wireless/core.c

@@ -894,7 +894,7 @@ static int __init cfg80211_init(void)
 }
 subsys_initcall(cfg80211_init);
 
-static void cfg80211_exit(void)
+static void __exit cfg80211_exit(void)
 {
 	debugfs_remove(ieee80211_debugfs_dir);
 	nl80211_exit();