ath9k: Fetch appropriate operating channel context

Retrieve appropriate operating channel context while switching
between operating and off channels.

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/channel.c
Simple merge

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