media: Kconfig: Don't expose the Request API option

The Request API isn't meant to be chosen by users,
but instead should be selected by drivers that want
to support it.

Hantro and Cedrus are already selecting the right options,
so only the test drivers need to be fixed.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>