[media] pwc: Replace control code with v4l2-ctrls framework

Also remove all the converting from native range to 0-65535 and back
that was going on. This is no longer needed now that we no longer support
v4l1.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>