media: vivid: drop bitmap and clipping output overlay support

This test driver is the only remaining driver still using
the clipping and bitmap method. Drop support for this so
we can remove this in the V4L2 API as well.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>