fdt: Export the fdt_find_or_add_subnode() function

This function is useful for ensuring that a node exists. Export it so it
can be used more widely.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Anatolij Gustschin <agust@denx.de>
Reviewed-by: Tom Rini <trini@ti.com>
diff --git a/common/fdt_support.c b/common/fdt_support.c
index 3f64156..46a15e7 100644
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -113,7 +113,8 @@
 }
 
 /**
- * fdt_find_or_add_subnode - find or possibly add a subnode of a given node
+ * fdt_find_or_add_subnode() - find or possibly add a subnode of a given node
+ *
  * @fdt: pointer to the device tree blob
  * @parentoffset: structure block offset of a node
  * @name: name of the subnode to locate
@@ -121,8 +122,7 @@
  * fdt_subnode_offset() finds a subnode of the node with a given name.
  * If the subnode does not exist, it will be created.
  */
-static int fdt_find_or_add_subnode(void *fdt, int parentoffset,
-				   const char *name)
+int fdt_find_or_add_subnode(void *fdt, int parentoffset, const char *name)
 {
 	int offset;