mac80211: add might_sleep to hw_config

Just to catch bugs when changing mac80211.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index ab8a860..ffff549 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -203,6 +203,8 @@
 	int ret = 0;
 	int power;
 
+	might_sleep();
+
 	if (local->sw_scanning)
 		chan = local->scan_channel;
 	else