ath9k_hw: add an extra delay when reseting AR_RTC_RESET

Without this we could start trying to work with the device without
it being fully functional yet and loose some packets upon resume.

Cc: Aeolus Yang <aeolus.yang@atheros.com>
Cc: Madhan Jaganathan <madhan.jaganathan@atheros.com>
signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -1070,6 +1070,7 @@ static bool ath9k_hw_set_reset_power_on(struct ath_hw *ah)
 		REG_WRITE(ah, AR_RC, AR_RC_AHB);
 
 	REG_WRITE(ah, AR_RTC_RESET, 0);
+	udelay(2);
 
 	REGWRITE_BUFFER_FLUSH(ah);
 	DISABLE_REGWRITE_BUFFER(ah);