[media] xc4000: turn off debug logging by default

Don't dump debug into to dmesg by default (something I had enabled during
bringup of the xc4000 driver).

Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>