[media] s5p-tv: remove dv_preset support from mixer_video

The dv_preset API is deprecated and is replaced by the much improved dv_timings
API. Remove the dv_preset support from this driver as this will allow us to
remove the dv_preset API altogether (s5p-tv being the last user of this code).

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Tested-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Acked-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>