[media] stv090x: On STV0903 do not set registers of the second path

Sometimes there is a problem when trying to access the non-existing registers
of the second demodulator path on the STV0903.

This change removes the calls in case the driver is used on a STV0903.

Signed-off-by: Andreas Regel <andreas.regel@gmx.de>
Acked-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>