media: staging: media: imx6-mipi-csi2: use devm_mutex_init() to simplify code

media: staging: media: imx6-mipi-csi2: use devm_mutex_init() to simplify code

Use devm_mutex_init() to simplify the code. No functional change.

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patch.msgid.link/20260116-stage-csi2-cleanup-v2-2-a56e9cb25196@nxp.com
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>