ath9k_hw: Fix handling of MCI interrupt

in my previous patches of handling MCI interrupt I overlooked
the case of interrupt status/mask variable being zeroed out in
the below code, so ath_isr does not cache the MCI interrupt
in the intrstatus. finally MCI interrupt handling won't be
handled in ath9k_tasklet for the scheduled interrupts.
Fix this by moving the MCI interrupt code in the appropriate
position in ar9003_hw_get_isr

Cc: Wilson Tsao <wtsao@qca.qualcomm.com>
Cc: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>