net/virtio: Fix failover_replug_primary() return value regression

net/virtio: Fix failover_replug_primary() return value regression

Commit 150ab54aa6 "net/virtio: fix re-plugging of primary device"
fixed failover_replug_primary() to return false on failure.  Commit
5a0948d36c "net/virtio: Fix failover error handling crash bugs" broke
it again for hotplug_handler_plug() failure.  Unbreak it.

Commit 5a0948d36c4cbc1c5534afac6fee99de55245d12

Fixes: 5a0948d36c4cbc1c5534afac6fee99de55245d12
Cc: Jens Freimann <jfreimann@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Jens Freimann <jfreimann@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20200630090351.1247703-2-armbru@redhat.com>