dvb: fix problem stopping DVB-S muxes being added on DVB v3 systems
(cherry picked from commit 23f788ff2b354fe1812ebaf2d934330fe0ff9404)
Fix #1679 - correct mistake in previous changes to stop constant IO

TSID was not being properly updated, which could result in missing
services.
(cherry picked from commit 8bceacd96966211eddbd5cb1784e0f3864451483)