ath9k_hw: Updated AR9462 initval table to improve rx performance

The initval tables are updated as per system team input to improve
rx performance and power accuracy at 5GHz.

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