[media] af9033: return 0.1 dB DVBv3 SNR for AF9030 family

Previous patch changed both AF9030 and IT9130 SNR reporting from
dB to relative. Restore AF9030 to old behavior as it has been always
returning 0.1 dB value. Leave IT9130 relative as old IT9130 was
returning relative values.

Cc: Bimow Chen <Bimow.Chen@ite.com.tw>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>