Rockchip platform suppose to use TPL(run in SRAM) as dram init and
SPL(run in DDR SDRAM) as pre-loader, so that the SPL would not be
limited by SRAM size.
This patch add rk3399-board-tpl.c and its common configs.
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
