[media] af9033: implement .read_snr()

Returns values as 0.1 dB resolution as preferred nowadays.
Actual resolution is 1 dB.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
2 files changed