[media] saa7164: fix HVR2255 ATSC inversion issue

QAM mode in the LGDT3306 auto detects inversion. VSB does not.
Forgot to include tis fact in the original patch set.
Tested with QAM and VSB after this patch, working fine.

Signed-off-by: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>