media: i2c: st-mipid02: correct format propagation

Use a copy of the struct v4l2_subdev_format when propagating
format from the sink to source pad in order to avoid impacting the
sink format returned to the application.

Thanks to Jacopo Mondi for pointing the issue.

Fixes: 6c01e6f3

 ("media: st-mipid02: Propagate format from sink to source pad")
Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Cc: stable@vger.kernel.org
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Benjamin Mugnier <benjamin.mugnier@foss.st.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>