dm: core: Avoid creating a name property when unflattening

The current implementation creates a 'name' value for every node. This
is not needed for the latest device tree format, which includes a name in
the node header.

Adjust the code to point the name at the node header instead.

Also simplify ofnode_get_name(), now that we can rely on it to set the
name correctly. Update the comment to make it clear what name the root
node has.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/core/ofnode.c

@@ -356,7 +356,7 @@ const char *ofnode_get_name(ofnode node)
 	}
 
 	if (ofnode_is_np(node))
-		return strrchr(node.np->full_name, '/') + 1;
+		return node.np->name;
 
 	return fdt_get_name(gd->fdt_blob, ofnode_to_offset(node), NULL);
 }