ath9k: fix checks for first subframe delimiter padding

The commit "ath9k_hw: Fix exceed transmission burst-time of 5GHz" added
a padding of 60 delimiters on the first subframe to work around an issue
on AR9380, but it lacked the checks to prevent it from being applied to
pre-AR9380, enterprise AR9380 or AR9580+

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Cc: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 68066c5..29bcc55 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -709,7 +709,8 @@
 	 * Add delimiter when using RTS/CTS with aggregation
 	 * and non enterprise AR9003 card
 	 */
-	if (first_subfrm)
+	if (first_subfrm && !AR_SREV_9580_10_OR_LATER(sc->sc_ah) &&
+	    (sc->sc_ah->ent_mode & AR_ENT_OTP_MIN_PKT_SIZE_DISABLE))
 		ndelim = max(ndelim, FIRST_DESC_NDELIMS);
 
 	/*