rtlwifi: Improve handling of IPv6 packets

Routine rtl_is_special_data() is supposed to identify packets that need to
use a low bit rate so that the probability of successful transmission is
high. The current version has a bug that causes all IPv6 packets to be
labelled as special, with a corresponding low rate of transmission. A
complete fix will be quite intrusive, but until that is available, all
IPv6 packets are identified as regular.

This patch also removes a magic number.

Reported-and-tested-by: Alan Fisher <acf@unixcube.org>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org> [3.18+]
Cc: Alan Fisher <acf@unixcube.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/rtlwifi/base.c

@@ -1386,8 +1386,11 @@ u8 rtl_is_special_data(struct ieee80211_hw *hw, struct sk_buff *skb, u8 is_tx)
 		}
 
 		return true;
-	} else if (0x86DD == ether_type) {
-		return true;
+	} else if (ETH_P_IPV6 == ether_type) {
+		/* TODO: Handle any IPv6 cases that need special handling.
+		 * For now, always return false
+		 */
+		goto end;
 	}
 
 end: