ath9k_hw: Add support for MCI WLAN calibration

WLAN communicates with BT for its calibration by sending WLAN_CAL_REQ,
waits for BT_CAL_GRANT. This is done with the help of GPM messages.
also WLAN_CAL_DONE messages is sent once WLAN calibration is done.

Cc: Wilson Tsao <wtsao@qca.qualcomm.com>
Cc: Senthil Balasubramanian <senthilb@qca.qualcomm.com>
Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>