ath9k: allow setting arbitrary antenna masks on AR9003+

Cc: stable@vger.kernel.org
Signed-off-by: NFelix Fietkau <nbd@openwrt.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

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

@@ -1826,6 +1826,9 @@ static u32 fill_chainmask(u32 cap, u32 new)
 
 static bool validate_antenna_mask(struct ath_hw *ah, u32 val)
 {
+	if (AR_SREV_9300_20_OR_LATER(ah))
+		return true;
+
 	switch (val & 0x7) {
 	case 0x1:
 	case 0x3: