common: Move device-tree setup functions to fdt_support.h

These functions relate to setting up the device tree for booting the OS.
The fdt_support.h header file supports similar functions, so move these
there.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/ve8313/ve8313.c b/board/ve8313/ve8313.c
index 781a07f..2ea762c 100644
--- a/board/ve8313/ve8313.c
+++ b/board/ve8313/ve8313.c
@@ -9,6 +9,7 @@
  */
 
 #include <common.h>
+#include <fdt_support.h>
 #include <init.h>
 #include <linux/libfdt.h>
 #include <pci.h>