media: i2c: imx219: Implement .init_cfg() using .set_fmt()

Instead of duplicating the logical implemented in the .set_fmt()
operation in .init_cfg(), call .set_fmt() directly. This centralizes the
format and crop rectangle calculations in a single place.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>