ath9k: Proper TX99 interrupt ref count

On TX99 mode, instead of assuming interrupt mask non ATH9K_INT_GLOBAL,
let ath9k_hw_disable_interrupts proper set interrupt ref count.
This prevents some PCI PERR occurring specialy when setting 11b and n rates.

Signed-off-by: Eduardo Abinader <eduardo.abinader@riverbed.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath9k/tx99.c

@@ -132,7 +132,6 @@ static int ath9k_tx99_init(struct ath_softc *sc)
 	ath9k_ps_wakeup(sc);
 
 	ath9k_hw_disable_interrupts(ah);
-	atomic_set(&ah->intr_ref_cnt, -1);
 	ath_drain_all_txq(sc);
 	ath_stoprecv(sc);