wifi: rtw88: check the return value of alloc_workqueue()

The function alloc_workqueue() in rtw_core_init() can fail, but
there is no check of its return value. To fix this bug, its return value
should be checked with new error handling code.

Fixes: fe101716 ("rtw88: replace tx tasklet with work queue")
Reported-by: Hacash Robot <hacashRobot@santino.com>
Signed-off-by: William Dean <williamsukatube@gmail.com>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220723063756.2956189-1-williamsukatube@163.com

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

@@ -1992,6 +1992,10 @@ int rtw_core_init(struct rtw_dev *rtwdev)
 	timer_setup(&rtwdev->tx_report.purge_timer,
 		    rtw_tx_report_purge_timer, 0);
 	rtwdev->tx_wq = alloc_workqueue("rtw_tx_wq", WQ_UNBOUND | WQ_HIGHPRI, 0);
+	if (!rtwdev->tx_wq) {
+		rtw_warn(rtwdev, "alloc_workqueue rtw_tx_wq failed\n");
+		return -ENOMEM;
+	}
 
 	INIT_DELAYED_WORK(&rtwdev->watch_dog_work, rtw_watch_dog_work);
 	INIT_DELAYED_WORK(&coex->bt_relink_work, rtw_coex_bt_relink_work);