ath11k: unlock on error path in ath11k_mac_op_add_interface()

These error paths need to drop the &ar->conf_mutex before returning.

Fixes: 690ace20 ("ath11k: peer delete synchronization with firmware")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/X85sVGVP/0XvlrEJ@mwanda

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

@@ -4615,13 +4615,13 @@ static int ath11k_mac_op_add_interface(struct ieee80211_hw *hw,
 		if (ret) {
 			ath11k_warn(ar->ab, "failed to delete peer vdev_id %d addr %pM\n",
 				    arvif->vdev_id, vif->addr);
-			return ret;
+			goto err;
 		}
 
 		ret = ath11k_wait_for_peer_delete_done(ar, arvif->vdev_id,
 						       vif->addr);
 		if (ret)
-			return ret;
+			goto err;
 
 		ar->num_peers--;
 	}