rockchip: use puts instead of printf when back to bootrom

rockchip: use puts instead of printf when back to bootrom

printf will increase the code size more than 1kb, but platform
like rk3036 has no enough space for it.

Signed-off-by: Andy Yan <[email protected]>
Acked-by: Philipp Tomsich <[email protected]>
Reviewed-by: Philipp Tomsich <[email protected]>