drivers: video: Enable necessary video functions at SPL

To support video driver at SPL use CONFIG_IS_ENABLED and CONFIG_VAL,
which checks for stage specific configs and thus enables video support
at respective stage.

Signed-off-by: Nikhil M Jain <n-jain1@ti.com>
Reviewed-by: Devarsh Thakkar <devarsht@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>