ath5k: apply the synth voltage tweak only on AR5112 rev 2

Might fix some stability issues on newer chips
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Acked-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath5k/phy.c

@@ -970,6 +970,8 @@ static int ath5k_hw_rfregs_init(struct ath5k_hw *ah,
 			}
 
 			/* Lower synth voltage on Rev 2 */
+			if (ah->ah_radio == AR5K_RF5112 &&
+			    (ah->ah_radio_5ghz_revision & AR5K_SREV_REV) > 0) {
 				ath5k_hw_rfb_op(ah, rf_regs, 2,
 						AR5K_RF_HIGH_VC_CP, true);
 
@@ -981,6 +983,7 @@ static int ath5k_hw_rfregs_init(struct ath5k_hw *ah,
 
 				ath5k_hw_rfb_op(ah, rf_regs, 2,
 						AR5K_RF_PUSH_UP, true);
+			}
 
 			/* Decrease power consumption on 5213+ BaseBand */
 			if (ah->ah_phy_revision >= AR5K_SREV_PHY_5212A) {