V4L/DVB (9450): Code Review: #4 Consolidate configurations

* Better readability
* Avoids duplication

Comments from Oliver Endriss <o.endriss@gmx.de>

Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>