media: nxp: Stop direct calls to queue num_buffers field

media: nxp: Stop direct calls to queue num_buffers field

Use vb2_get_num_buffers() to avoid using queue num_buffers field directly.
This allows us to change how the number of buffers is computed in the
future.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Reviewed-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
CC: Rui Miguel Silva <rmfrfs@gmail.com>
CC: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
CC: Martin Kepplinger <martink@posteo.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>