mcd_account_process_initial_avatar_token: don't take self_contact argument
mcd_account_process_initial_avatar_token: don't take self_contact argument

It can be retrieved from the McdAccount.

freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control