mpt3sas: avoid mpt3sas_transport_port_add NULL parent_dev

If _scsih_sas_host_add's call to mpt3sas_config_get_sas_iounit_pg0
fails, ioc->sas_hba.parent_dev may be left uninitialized.  A later
device probe could invoke mpt3sas_transport_port_add which will call
sas_port_alloc_num [scsi_transport_sas] with a NULL parent_dev pointer.
Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
Acked-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/mpt3sas/mpt3sas_transport.c

@@ -705,6 +705,11 @@ mpt3sas_transport_port_add(struct MPT3SAS_ADAPTER *ioc, u16 handle,
 		goto out_fail;
 	}
 
+	if (!sas_node->parent_dev) {
+		pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",
+		    ioc->name, __FILE__, __LINE__, __func__);
+		goto out_fail;
+	}
 	port = sas_port_alloc_num(sas_node->parent_dev);
 	if ((sas_port_add(port))) {
 		pr_err(MPT3SAS_FMT "failure at %s:%d/%s()!\n",