This patch add a loaderimage for rockchip miniloader,
supports uboot and ATF/trust os.

usage:
./tools/loaderimage [--pack|--unpack] [--uboot|--trustos] file_in
file_out

Change-Id: Ibafb494ab64ed9c7d46fa3f4b6ccbd70a9fcee86
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>