qla4xxx: check the return value of dma_alloc_coherent()

the qla4xxx_alloc_fw_dump() calls dma_alloc_coherent() but does not
check its return value.
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Acked-By: Nilesh Javali <nilesh.javali@qlogic.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/scsi/qla4xxx/ql4_init.c

@@ -334,6 +334,12 @@ void qla4xxx_alloc_fw_dump(struct scsi_qla_host *ha)
 	/* Allocate memory for saving the template */
 	md_tmp = dma_alloc_coherent(&ha->pdev->dev, ha->fw_dump_tmplt_size,
 				    &md_tmp_dma, GFP_KERNEL);
+	if (!md_tmp) {
+		ql4_printk(KERN_INFO, ha,
+			   "scsi%ld: Failed to allocate DMA memory\n",
+			   ha->host_no);
+		return;
+	}
 
 	/* Request template */
 	status =  qla4xxx_get_minidump_template(ha, md_tmp_dma);