ath9k_hw: fix incorrect LNA register settings

After a full reset, mci_reset will put LNA update to the setting
for 2G mode. Those registers need to be forced to update when
the channel is in 5G.

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