media: ti-vpe: cal: Add context V4L2 cleanup and unregister functions

Create cal_ctx_v4l2_unregister() and cal_ctx_v4l2_cleanup() functions to
unregister and cleanup the V4L2-related objects from the context, and
call them in cal_remove() and in the error path of cal_probe().

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>