V4L/DVB (5929): Add vp27smpx driver

This device is internal to the Panasonic VP27S tuner and is used to set 
the mono/stereo/bilingual setting of the tuner.

It is used by two Japanese cx23416-based cards.

Signed-off-by: Takahiro Adachi <tadachi@tadachi-net.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>