media: ti-vpe: cal: add 'use_pix_proc' field

We already have functions to reserve and release a pix proc unit, but we
always reserve such and the code expects the pix proc unit to be used.

Add a new field, 'use_pix_proc', to indicate if the pix prox unit has
been reserved and should be used. Use the flag to skip programming pix
proc unit when not needed.

Note that we still always set the use_pix_proc flag to true.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>