All callers of get_event_dest_clienter() pass 0 to the filter
argument, and it means that the check there is utterly redundant.

Drop the superfluous filter argument and its check as a code cleanup.

Link: https://patch.msgid.link/20240819084757.11902-1-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>