dm: core: Add a place to put extra device-tree reading functions

Some functions deal with structured data rather than simple data types.
It makes sense to have these in their own file. For now this just has a
function to read a flashmap entry. Move the data types also.

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

lib/fdtdec.c

@@ -12,6 +12,7 @@
 #include <fdt_support.h>
 #include <fdtdec.h>
 #include <asm/sections.h>
+#include <dm/of_extra.h>
 #include <linux/ctype.h>
 
 DECLARE_GLOBAL_DATA_PTR;