qcacld-3.0: Avoid dereferencing null tx_desc in ol_tx_ll_fast

In one version of ol_tx_ll_fast a null tx_desc will be dereferenced.
ol_tx_desc_vdev_update is called when tx_desc is guaranteed to not
be null. Move the vdev_id assignment into ol_tx_desc_vdev_update
to simplify the code and fix the null pointer dereference.

Change-Id: I01b2e81ee3f19cdf3f2f74ccc575df767891f472
CRs-Fixed: 2020708

core/dp/txrx/ol_tx_desc.c

@@ -104,6 +104,7 @@ ol_tx_desc_vdev_update(struct ol_tx_desc_t *tx_desc,
 		       struct ol_txrx_vdev_t *vdev)
 {
 	tx_desc->vdev = vdev;
+	tx_desc->vdev_id = vdev->vdev_id;
 }
 
 #ifdef CONFIG_PER_VDEV_TX_DESC_POOL
@@ -156,8 +157,6 @@ struct ol_tx_desc_t *ol_tx_desc_alloc(struct ol_txrx_pdev_t *pdev,
 	if (!tx_desc)
 		return NULL;
 
-	tx_desc->vdev_id = vdev->vdev_id;
-
 	ol_tx_desc_vdev_update(tx_desc, vdev);
 	ol_tx_desc_count_inc(vdev);
 	qdf_atomic_inc(&tx_desc->ref_cnt);
@@ -224,8 +223,6 @@ struct ol_tx_desc_t *ol_tx_desc_alloc(struct ol_txrx_pdev_t *pdev,
 		pdev->pool_stats.pkt_drop_no_pool++;
 	}
 
-	tx_desc->vdev_id = vdev->vdev_id;
-
 	return tx_desc;
 }