Si2148-A20 silicon tuner support.

[Antti: Resolved conflict]
Signed-off-by: NEvgeny Plehov <EvgenyPlehov@ukr.net>
Signed-off-by: NAntti Palosaari <crope@iki.fi>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>