libfdt: Drop inlining of fdt_path_offset()

The fdt_path_offset() function is not inlined in upstream libfdt. Adjust
U-Boot's version to match.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/libfdt.h b/include/libfdt.h
index 398748c..8746790 100644
--- a/include/libfdt.h
+++ b/include/libfdt.h
@@ -410,10 +410,7 @@
  *	-FDT_ERR_BADSTRUCTURE,
  *	-FDT_ERR_TRUNCATED, standard meanings.
  */
-static inline int fdt_path_offset(const void *fdt, const char *path)
-{
-	return fdt_path_offset_namelen(fdt, path, strlen(path));
-}
+int fdt_path_offset(const void *fdt, const char *path);
 
 /**
  * fdt_get_name - retrieve the name of a given node