video: Add a Kconfig option for SPL video handoff

video: Add a Kconfig option for SPL video handoff

At present this feature is enabled in SPL if a bloblist is available.
Some platforms may not want to use this, so add an option to allow the
feature to be disabled.

Note that the feature unfortunately only fills in part of the
video-handoff information, so causes failures on x86 platforms. For now,
disable it there.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com> # qemu-x86_64