Add information that will be needed for enabling the UEFI capsule
update feature on the RockPi4 boards. With the feature enabled, it
would be possible to update the idbloader and u-boot.itb images on the
RockPi4B and RockPi4C variants.
Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>