ath11k: Fix memory leak in ath11k_qmi_driver_event_work

The buffer pointed to by event is not freed in case
ATH11K_FLAG_UNREGISTERING bit is set, resulting in
memory leak, so fix it.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-01720.1-QCAHSPSWPL_V1_V2_SILICONZ_LITE-1

Fixes: d5c65159 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Signed-off-by: Baochen Qiang <bqiang@codeaurora.org>
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210913180246.193388-4-jouni@codeaurora.org

drivers/net/wireless/ath/ath11k/qmi.c

@@ -2759,8 +2759,10 @@ static void ath11k_qmi_driver_event_work(struct work_struct *work)
 		list_del(&event->list);
 		spin_unlock(&qmi->event_lock);
 
-		if (test_bit(ATH11K_FLAG_UNREGISTERING, &ab->dev_flags))
+		if (test_bit(ATH11K_FLAG_UNREGISTERING, &ab->dev_flags)) {
+			kfree(event);
 			return;
+		}
 
 		switch (event->type) {
 		case ATH11K_QMI_EVENT_SERVER_ARRIVE: