media: imx-jpeg: Simplify descriptor initialization with memset

media: imx-jpeg: Simplify descriptor initialization with memset

Use memset() to zero-initialize desc and cfg_desc structures instead of
assigning individual fields to zero. This is cleaner and ensures all
descriptor fields are properly initialized.

No functional change.

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Ming Qian <ming.qian@oss.nxp.com>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>