ath9k_hw: fix BT mute at hw init

WLAN driver initialization is muting BT which is terminating
the ongoing BT traffic. The reason to mute BT is to avoid any
incoming MCI messages from BT when MCI reset is in progress that
could corrupt WLAN MCI RX state machine. But we should not
dedicate radio completely to WLAN in driver init itself. So this
patch removes the wlan weightage changes from mute BT to retain
BT connection.

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