ibmvscsi: Use of_root to access OF device tree root node

The root node of the OF device tree is exported as of_root. No need to
look up the root by path name. Instead just get a reference directly via
of_root.
Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ibmvscsi/ibmvscsi.c

@@ -248,25 +248,23 @@ static void ibmvscsi_task(void *data)
 
 static void gather_partition_info(void)
 {
-	struct device_node *rootdn;
-
 	const char *ppartition_name;
 	const __be32 *p_number_ptr;
 
 	/* Retrieve information about this partition */
-	rootdn = of_find_node_by_path("/");
-	if (!rootdn) {
+	if (!of_root)
 		return;
-	}
 
-	ppartition_name = of_get_property(rootdn, "ibm,partition-name", NULL);
+	of_node_get(of_root);
+
+	ppartition_name = of_get_property(of_root, "ibm,partition-name", NULL);
 	if (ppartition_name)
 		strncpy(partition_name, ppartition_name,
 				sizeof(partition_name));
-	p_number_ptr = of_get_property(rootdn, "ibm,partition-no", NULL);
+	p_number_ptr = of_get_property(of_root, "ibm,partition-no", NULL);
 	if (p_number_ptr)
 		partition_number = of_read_number(p_number_ptr, 1);
-	of_node_put(rootdn);
+	of_node_put(of_root);
 }
 
 static void set_adapter_info(struct ibmvscsi_host_data *hostdata)