ath9k_hw: Fix incorrect spur_freq_sd for AR9003

Spur frequency was incorrectly computed with 10Mhz offset
which could cause the filter would not notch out the spur
and also this could improve rx sensitivity in HT40.

Cc: Madhan Jaganathan <madhanj@qca.qualcomm.com>
Signed-off-by: NRajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/ar9003_phy.c

@@ -370,7 +370,7 @@ static void ar9003_hw_spur_ofdm_work(struct ath_hw *ah,
 			else
 				spur_subchannel_sd = 0;
 
-			spur_freq_sd = ((freq_offset + 10) << 9) / 11;
+			spur_freq_sd = (freq_offset << 9) / 11;
 
 		} else {
 			if (REG_READ_FIELD(ah, AR_PHY_GEN_CTRL,
@@ -379,7 +379,7 @@ static void ar9003_hw_spur_ofdm_work(struct ath_hw *ah,
 			else
 				spur_subchannel_sd = 1;
 
-			spur_freq_sd = ((freq_offset - 10) << 9) / 11;
+			spur_freq_sd = (freq_offset << 9) / 11;
 
 		}