[media] tm6000: bugfix data check

beholder use a map with 3 bytes, but many rc maps have 2 bytes, so I add a workaround for beholder rc.

Signed-off-by: Stefan Ringel <linuxtv@stefanringel.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>