ath9k_hw: fix AR9462 2g5g switch on full reset

On full reset, mci reset will put LNA update on 2G mode. And
Whenever 2g5g_switch is forced at the end of full reset, lna
update should not be skipped. Not doing so, is affecting WLAN
rx and causing beacon loss when BTCOEX is enabled on AR9462.

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