[media] tvp7002: replace 'preset' by 'timings' in various structs/variables

This is the first step towards removing the deprecated preset support of this
driver.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Lad, Prabhakar <prabhakar.lad@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>