ofnode: add {ofnode, dev}_read_resource_byname()

Linux supports platform_get_resource_byname() to look up a resource
by name.

We want a similar helper.  It is useful when a device node has named
register regions.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/core/read.c

@@ -164,3 +164,9 @@ int dev_read_resource(struct udevice *dev, uint index, struct resource *res)
 {
 	return ofnode_read_resource(dev_ofnode(dev), index, res);
 }
+
+int dev_read_resource_byname(struct udevice *dev, const char *name,
+			     struct resource *res)
+{
+	return ofnode_read_resource_byname(dev_ofnode(dev), name, res);
+}