V4L/DVB (11675): ivtv/radio: fix V4L2_TUNER_MODE/V4L2_TUNER_SUB confusion

V4L2_TUNER_MODE_ was used in a few places where V4L2_TUNER_SUB_ should have
been used.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>