mt76: mt7615: add __aligned(4) to txp structs

The beginning of the struct is guaranteed to be 4-byte aligned, and this
attribute allows the compiler to generate more efficient code
Signed-off-by: NFelix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7615/mac.h

@@ -243,7 +243,7 @@ struct mt7615_txp {
 	u8 nbuf;
 	__le32 buf[MT_TXP_MAX_BUF_NUM];
 	__le16 len[MT_TXP_MAX_BUF_NUM];
-} __packed;
+} __packed __aligned(4);
 
 struct mt7615_tx_free {
 	__le16 rx_byte_cnt;
@@ -251,7 +251,7 @@ struct mt7615_tx_free {
 	u8 txd_cnt;
 	u8 rsv[3];
 	__le16 token[];
-} __packed;
+} __packed __aligned(4);
 
 #define MT_TX_FREE_MSDU_ID_CNT		GENMASK(6, 0)