[media] Mantis, hopper: use MODULE_DEVICE_TABLE

use the macro to make modules auto-loadable

Thanks to Ozan Çağlayan <ozan@pardus.org.tr> for pointing it out

Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>