mac80211: use 16 bit alignment for the if_ibss bssid field

Several MAC address comparison functions assume 16 bit alignment for pointers
passed to them. Since the addition of the control_port field, alignment
for the IBSS bssid was off by one, causing a severe performance hit on
architectures without efficient unaligned access (e.g. MIPS).
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/ieee80211_i.h

@@ -480,7 +480,7 @@ struct ieee80211_if_ibss {
 
 	bool control_port;
 
-	u8 bssid[ETH_ALEN];
+	u8 bssid[ETH_ALEN] __aligned(2);
 	u8 ssid[IEEE80211_MAX_SSID_LEN];
 	u8 ssid_len, ie_len;
 	u8 *ie;