media: imx-jpeg: Support to assign slot for encoder/decoder

imx jpeg encoder and decoder support 4 slots each,
aim to support some virtualization scenarios.

driver should only enable one slot one time.

but due to some hardware issue,
only slot 0 can be enabled in imx8q platform,
and they may be fixed in imx9 platform.

Signed-off-by: Ming Qian <ming.qian@nxp.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>