dm: core: add ofnode_get_path()

Add function for retrieving full node path of a given ofnode.
This uses np->full_name if OF is live, otherwise a call to
fdt_get_path() is made.

Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Tested-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

include/dm/ofnode.h

@@ -458,6 +458,16 @@ ofnode ofnode_get_parent(ofnode node);
  */
 const char *ofnode_get_name(ofnode node);
 
+/**
+ * ofnode_get_path() - get the full path of a node
+ *
+ * @node: valid node to look up
+ * @buf: buffer to write the node path into
+ * @buflen: buffer size
+ * @return 0 if OK, -ve on error
+ */
+int ofnode_get_path(ofnode node, char *buf, int buflen);
+
 /**
  * ofnode_get_by_phandle() - get ofnode from phandle
  *