ar71xx: add an external reset callback for ar913x and use it in ath9k - should reduce the frequency of DMA stop failures

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@36530 3c298f89-4303-0410-b956-a3cf2f4a3e73
mac80211: merge a client mode channel switch handling fix

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@36531 3c298f89-4303-0410-b956-a3cf2f4a3e73