ath9k_hw: Add radio retention support for AR9480

Supported calibrations of radio retention table (RTT) are
	- DC offset
	- Filter
	- Peak detect

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