ath9k: Fix QuickDrop usage

Bit 5 in the miscConfiguration field of the base EEPROM
header denotes whether QuickDrop is enabled or not. Fix
the incorrect usage of BIT(1) and also make sure that
this is done only for the required chips.

Cc: stable@vger.kernel.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/ar9003_eeprom.c

@@ -3984,18 +3984,20 @@ static void ar9003_hw_quick_drop_apply(struct ath_hw *ah, u16 freq)
 	int quick_drop;
 	s32 t[3], f[3] = {5180, 5500, 5785};
 
-	if (!(pBase->miscConfiguration & BIT(1)))
+	if (!(pBase->miscConfiguration & BIT(4)))
 		return;
 
-	if (freq < 4000)
-		quick_drop = eep->modalHeader2G.quick_drop;
-	else {
-		t[0] = eep->base_ext1.quick_drop_low;
-		t[1] = eep->modalHeader5G.quick_drop;
-		t[2] = eep->base_ext1.quick_drop_high;
-		quick_drop = ar9003_hw_power_interpolate(freq, f, t, 3);
+	if (AR_SREV_9300(ah) || AR_SREV_9580(ah) || AR_SREV_9340(ah)) {
+		if (freq < 4000) {
+			quick_drop = eep->modalHeader2G.quick_drop;
+		} else {
+			t[0] = eep->base_ext1.quick_drop_low;
+			t[1] = eep->modalHeader5G.quick_drop;
+			t[2] = eep->base_ext1.quick_drop_high;
+			quick_drop = ar9003_hw_power_interpolate(freq, f, t, 3);
+		}
+		REG_RMW_FIELD(ah, AR_PHY_AGC, AR_PHY_AGC_QUICK_DROP, quick_drop);
 	}
-	REG_RMW_FIELD(ah, AR_PHY_AGC, AR_PHY_AGC_QUICK_DROP, quick_drop);
 }
 
 static void ar9003_hw_txend_to_xpa_off_apply(struct ath_hw *ah, bool is2ghz)