Use &error_abort instead of separate assert()

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200313170517.22480-2-armbru@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[Unused Error *variable deleted]
3 files changed