ath9k_hw: prevent reset control register zeroing on AR9003 reset

Also, no need for the udelay(2) on AR9003 hardware.
Signed-off-by: Senthil Balasubramanian <senthilkumar@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

@@ -1385,9 +1385,11 @@ 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);
 
-	if (!AR_SREV_9100(ah))
+	if (!AR_SREV_9300_20_OR_LATER(ah))
+		udelay(2);
+
+	if (!AR_SREV_9100(ah) && !AR_SREV_9300_20_OR_LATER(ah))
 		REG_WRITE(ah, AR_RC, 0);
 
 	REG_WRITE(ah, AR_RTC_RESET, 1);