[media] cxd2820r: wait demod lock for DVB-C too
Fix yet another bug introduced be recent cxd2820r multi-frontend to
single-frontend change.
Finally, we have at least almost working picture for DVB-C too.
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>