ath9k: Fix MCI reset in BT cal_req

This patch reverts the commit "ath9k_hw: Wait BT calibration to complete"
and bail out from MCI interrupt routine for chip reset. The above commit
stalls the WLAN TCP traffic while bringing up and down the BT interface
iteratively. Fixing this properly by queueing up chip reset and bailing
out properly from tasklet routine.

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