[media] saa7164: fix input and tuner compliance problems

- the frequency range was never set
- there was no initial frequency
- missing index/tuner checks
- inconsistent standard reporting
- removed unnecessary tuner type checks (the core handles that)
- clamp frequency to the valid frequency range as per the V4L2 spec

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>