V4L/DVB: tuner-xc2028: Fix demod breakage for XC3028L

A small mistake on the last patch broke demod s-code setup for
XC3028L (firmware 3.2 and upper). Fix it.

Thanks-to: Stefan Ringel <stefan.ringel@arcor.de>

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>