[media] cpia2: major overhaul to get it in a working state again

This driver was severely broken. This patch makes it work again, and updates
it to the latest V4L2 frameworks (except for videobuf2). It passes the
v4l2-compliance tests and it now handles suspend/resume correctly.

Several custom controls are replaced by new standard controls, only the
USB_ALTERNATE control remains.

Tested with the Hanse HVS-CM500PC USB microscope.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>