media: v4l2-mediabus: Drop legacy V4L2_MBUS_CSI2_*_LANE flags

The V4L2_MBUS_CSI2_*_LANE flags are a legacy API and are unused. Drop
them.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>