media: i2c: imx219: Initialize ycbcr_enc

media: i2c: imx219: Initialize ycbcr_enc

While the ycbcr_enc field doesn't apply to raw formats, leaving it
uninitialized makes the driver behave in a less deterministic way. Fix
it by picking the default value for the colorspace.

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>