media: add default settings and module parameters for video controls

This patch adds parameter definitions and module parameters for the four
userspace controls that the SUR40 can currently provide.

Signed-off-by: Florian Echtler <floe@butterbrot.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>