ath9k: Fix build error on ARM

Use mdelay instead of udelay to fix this error:

ERROR: "__bad_udelay" [drivers/net/wireless/ath/ath9k/ath9k_hw.ko] undefined!
make[1]: *** [__modpost] Error 1
make: *** [modules] Error 2
Reported-by: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -1316,7 +1316,7 @@ static bool ath9k_hw_set_reset(struct ath_hw *ah, int type)
 	if (AR_SREV_9300_20_OR_LATER(ah))
 		udelay(50);
 	else if (AR_SREV_9100(ah))
-		udelay(10000);
+		mdelay(10);
 	else
 		udelay(100);
 
@@ -2051,9 +2051,8 @@ static bool ath9k_hw_set_power_awake(struct ath_hw *ah)
 
 	REG_SET_BIT(ah, AR_RTC_FORCE_WAKE,
 		    AR_RTC_FORCE_WAKE_EN);
-
 	if (AR_SREV_9100(ah))
-		udelay(10000);
+		mdelay(10);
 	else
 		udelay(50);