[media] s5p-tv: hdmiphy: Remove deprecated video-level DV timings operation

The video enum_dv_timings operation is deprecated and unused. Remove it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>