mt76: mt7921: remove unneeded semicolon

Fix the following coccicheck warnings:

./drivers/net/wireless/mediatek/mt76/mt7921/mac.c:1402:2-3: Unneeded
semicolon.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7921/mac.c

@@ -1400,7 +1400,7 @@ void mt7921_mac_work(struct work_struct *work)
 	if (++phy->sta_work_count == 10) {
 		phy->sta_work_count = 0;
 		mt7921_mac_sta_stats_work(phy);
-	};
+	}
 
 	mt7921_mutex_release(phy->dev);