ath9k: add a fix for tx queueing and aggregation

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

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@40586 3c298f89-4303-0410-b956-a3cf2f4a3e73
update ar71xx kernel to 3.12.17
fix compile errors 3.12 on ar71xx
update u-boot-lantiq-2013.10 to openwrt6