media: v4l2-core: drop v4l2_window clipping and bitmap support

There are no longer any drivers that support clipping and bitmap
support for the capture or output overlay interfaces, so drop
this.

Always set the bitmap, clips and clipcount fields to 0, and
remove the compat32 support.

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