qcacmn: Fix a locking issue in DP Tx error path

There is a possiblility of invoking spin_unlock without taking
spin_lock in DP tx descriptor prepare function in error path.
This change fixes this issue.

Change-Id: Id4c5c0115b14041865e7f97f930e7023e865eca2
CRs-Fixed: 2088616

dp/wifi3.0/dp_tx.c

@@ -994,7 +994,7 @@ static qdf_nbuf_t dp_tx_send_msdu_single(struct dp_vdev *vdev, qdf_nbuf_t nbuf,
 		QDF_TRACE(QDF_MODULE_ID_DP, QDF_TRACE_LEVEL_ERROR,
 			  "%s Tx_desc prepare Fail vdev %p queue %d\n",
 			  __func__, vdev, tx_q->desc_pool_id);
-		goto fail_return;
+		return nbuf;
 	}
 
 	if (qdf_unlikely(hal_srng_access_start(soc->hal_soc, hal_srng))) {