dvbapi: Improve Irdeto/Beta EMM tunnel.

- EMM tunnel now also depends on the betatunnel service-ids.
- It is possible to specify betatunnel with srvid=0000 to activate EMM-only tunnel.
- Some minor code improvements as suggested by user depp0n.

Patch by canna posted in ticket #3258.

git-svn-id: http://streamboard.de.vu/svn/oscam/trunk@8566 4b0bc96b-bc66-0410-9d44-ebda105a78c1