rockchip: doc: clarify usage of CONFIG_SPL_ROCKCHIP_BACK_TO_BROM

Change the description relating to CONFIG_SPL_ROCKCHIP_BACK_TO_BROM to
clarify that both RK3288 and RK3036 use

	CONFIG_SPL_ROCKCHIP_BACK_TO_BROM=y

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
1 file changed