vhost: setup error eventfd and dump errors

vhost: setup error eventfd and dump errors

Vhost has error notifications, let's log them like other errors.
For each virt-queue setup eventfd for vring error notifications.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
[vsementsov: rename patch, change commit message  and dump error like
             other errors in the file]
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-Id: <20220623161325.18813-3-vsementsov@yandex-team.ru>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Roman Kagan <rvkagan@yandex-team.ru>