ath9k: switch channel context for beaconing

Add a basic state machine for switch channel context
for beacon transmission.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --cc drivers/net/wireless/ath/ath9k/ath9k.h
Simple merge

diff --cc drivers/net/wireless/ath/ath9k/beacon.c
Simple merge

diff --cc drivers/net/wireless/ath/ath9k/channel.c
Simple merge

diff --cc drivers/net/wireless/ath/ath9k/main.c
Simple merge

diff --cc drivers/net/wireless/ath/ath9k/xmit.c
Simple merge