ath9k: Send WLAN channel info to BT

WLAN updates channel bitmap when associated and disassociated. Channel
bitmap will reflect whare are the channels used or affected by WLAN and
BT should avoid using those. Not doing so, could affect BT traffic
as both WLAN and BT is operating on same channel.

Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>