mac80211: update to 2013-01-07, add several ath9k stability fixes

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35063 3c298f89-4303-0410-b956-a3cf2f4a3e73
mac80211, ath9k: merge some pending fixes from linux-wireless@

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@35066 3c298f89-4303-0410-b956-a3cf2f4a3e73