[U-Boot] rockchip: rk3399: spl: convert to using BOOT_DEVICE_BOOTROM

[Philipp Tomsich]

> Instead of directly calling into the back-to-bootrom code, the RK3399
> common SPL implementation now uses BOOT_DEVICE_BOOTROM to trigger a
> transfer back into the bootrom.
> 
> With this factored out, the spl_board_init function can not be
> customised for each RK3399 board.
> 
> Signed-off-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>
> Reviewed-by: Simon Glass <sjg at chromium.org>
> ---
> 
>  arch/arm/mach-rockchip/rk3399-board-spl.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 

Applied to u-boot-rockchip, thanks!