media: imx-jpeg: Reset slot data pointers when freed

commit faa8051b upstream.

Ensure that the slot data pointers are reset to NULL and handles are
set to 0 after freeing the coherent memory. This makes he function
mxc_jpeg_alloc_slot_data() and mxc_jpeg_free_slot_data() safe to be
called multiple times.

Fixes: 2db16c6e ("media: imx-jpeg: Add V4L2 driver for i.MX8 JPEG Encoder/Decoder")
Cc: stable@vger.kernel.org
Signed-off-by: Ming Qian <ming.qian@oss.nxp.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>