madwifi: fix crash on ad-hoc interface init

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@12161 3c298f89-4303-0410-b956-a3cf2f4a3e73

package/madwifi/patches/378-adhoc_crash_fix.patch

+--- a/net80211/ieee80211_input.c
++++ b/net80211/ieee80211_input.c
+@@ -3522,6 +3522,11 @@
+ 		if (ic->ic_flags & IEEE80211_F_SCAN) {
+ 			ieee80211_add_scan(vap, &scan, wh, subtype, rssi, rtsf);
+ 		}
++
++		/* stop processing if the bss channel is not set up yet */
++		if (!ic->ic_bsschan || ic->ic_bsschan == IEEE80211_CHAN_ANYC)
++			break;
++
+ 		/* NB: Behavior of WDS-Link and Ad-Hoc is very similar here:
+ 		 * When we receive a beacon that belongs to the AP that we're
+ 		 * connected to, use it to refresh the local node info.