Unify serial_rockchip, and use the generic binding. Signed-off-by: Thomas Chou <thomas@wytron.com.tw> Reviewed-by: Tom Rini <trini@konsulko.com> Tested-by: Ariel D'Alessandro <ariel@vanguardiasur.com.ar> Acked-by: Simon Glass <sjg@chromium.org>