sandbox: config: enable fdt and snprintf() options

Enable fdt code and safe snprintf() options for sandbox.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

include/configs/sandbox.h

@@ -28,6 +28,12 @@
 /* Number of bits in a C 'long' on this architecture */
 #define CONFIG_SANDBOX_BITS_PER_LONG	64
 
+#define CONFIG_OF_CONTROL
+#define CONFIG_OF_LIBFDT
+#define CONFIG_LMB
+
+#define CONFIG_SYS_VSNPRINTF
+
 /*
  * Size of malloc() pool, although we don't actually use this yet.
  */