mvsas: fix error return code in mvs_task_prep()

Fix to return error code -ENOMEM from the error handling
case instead of 0, as done elsewhere in this function.
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NTejun Heo <tj@kernel.org>

drivers/scsi/mvsas/mv_sas.c

@@ -791,8 +791,10 @@ static int mvs_task_prep(struct sas_task *task, struct mvs_info *mvi, int is_tmf
 	slot->slot_tag = tag;
 
 	slot->buf = pci_pool_alloc(mvi->dma_pool, GFP_ATOMIC, &slot->buf_dma);
-	if (!slot->buf)
+	if (!slot->buf) {
+		rc = -ENOMEM;
 		goto err_out_tag;
+	}
 	memset(slot->buf, 0, MVS_SLOT_BUF_SZ);
 
 	tei.task = task;