[media] tlg2300: fix tuner and frequency handling of the radio device

This driver now passes the tuner and frequency tests of v4l2-compliance.
It's the usual bugs: frequency wasn't clamped to the valid frequency range,
incorrect tuner capabilities and tuner fields not filled in, missing test
for invalid tuner index, no initial frequency and incorrect error handling.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>