[media] it913x stop dual frontend attach in warm state with single devices

Stop dual frontend attach in warm state with single devices.

Since this is a no reconnect device this occurs only after a warm system
reboot.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>