fdt: introduce fdt_create_phandle()

The ePAPR specification says that phandle properties should be called
"phandle", and not "linux,phandle".  To facilitate the migration from
"linux,phandle" to "phandle", introduce function fdt_create_phandle(),
which creates a phandle in a given node.  For now, we create both the
"phandle" and "linux,phandle" properties.  A later version of this
function will remove support for "linux,phandle".

Signed-off-by: Timur Tabi <timur@freescale.com>
diff --git a/include/fdt_support.h b/include/fdt_support.h
index 382f632..863024f 100644
--- a/include/fdt_support.h
+++ b/include/fdt_support.h
@@ -89,6 +89,7 @@
 int fdt_node_offset_by_compat_reg(void *blob, const char *compat,
 					phys_addr_t compat_off);
 int fdt_alloc_phandle(void *blob);
+int fdt_create_phandle(void *fdt, int nodeoffset, uint32_t phandle);
 int fdt_add_edid(void *blob, const char *compat, unsigned char *buf);
 
 int fdt_verify_alias_address(void *fdt, int anode, const char *alias,