sandbox: Correct data sizes and printf() strings in fdtdec.c

sandbox: Correct data sizes and printf() strings in fdtdec.c

There are a few wwrnings in this file when building for sandbox. Addresses
coming from the device tree need to be treated as ulong as elsewhere in
U-Boot and we must use map_sysmem() to convert to a pointer when needed.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Hung-ying Tyan <tyanh@chromium.org>