avtp: crf: Remove superfluous sink_event variable
This variable was introduced by commit 12ad2a4b ("avtp: Introduce the CRF Sync Element") but it was never used:
$ git log -G "sink_event" -- ext/avtp
This variable was introduced by commit 12ad2a4b ("avtp: Introduce the CRF Sync Element") but it was never used:
$ git log -G "sink_event" -- ext/avtp