media: i2c: adv748x: Switch dv timing callbacks to pad ops

Change all (s|g|query)_dv_timings subdev callbacks to include
a pad argument.

Signed-off-by: Paweł Anikiel <panikiel@google.com>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>