qcacld-3.0: Add null check for vdev

To avoid null pointer access, in mlo_fw_ho_fail_req()
api add vdev null check.

Change-Id: Iabe6080f44b0a9cddba3f164697b07d9afc490b4
CRs-Fixed: 3173980

components/umac/mlme/mlo_mgr/src/wlan_mlo_mgr_roam.c

@@ -268,6 +268,11 @@ mlo_fw_ho_fail_req(struct wlan_objmgr_psoc *psoc,
 						    vdev_id,
 						    WLAN_MLME_SB_ID);
 
+	if (!vdev) {
+		mlo_err("vdev is null");
+		return;
+	}
+
 	if (!vdev->mlo_dev_ctx)
 		goto end;