rtw88: remove unused spinlock

dm_lock is never used. Thus, remove this redundant spinlock.
Signed-off-by: Tzu-En Huang <tehuang@realtek.com>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtw88/main.c

@@ -1376,7 +1376,6 @@ int rtw_core_init(struct rtw_dev *rtwdev)
 	skb_queue_head_init(&rtwdev->coex.queue);
 	skb_queue_head_init(&rtwdev->tx_report.queue);
 
-	spin_lock_init(&rtwdev->dm_lock);
 	spin_lock_init(&rtwdev->rf_lock);
 	spin_lock_init(&rtwdev->h2c.lock);
 	spin_lock_init(&rtwdev->txq_lock);

drivers/net/wireless/realtek/rtw88/main.h

@@ -1586,9 +1586,6 @@ struct rtw_dev {
 	/* ensures exclusive access from mac80211 callbacks */
 	struct mutex mutex;
 
-	/* lock for dm to use */
-	spinlock_t dm_lock;
-
 	/* read/write rf register */
 	spinlock_t rf_lock;