virtio: remove event notifier cleanup call on de-assign

virtio: remove event notifier cleanup call on de-assign

The virtio_bus_set_host_notifier function no longer calls
event_notifier_cleanup when a event notifier is removed.

The commit updates the code to match the new behavior and calls
virtio_bus_cleanup_host_notifier after the notifier was de-assign
and no longer in use.

This change is a preparation to allow executing the
virtio_bus_set_host_notifier function in a memory region
transaction.

Signed-off-by: Gal Hammer <[email protected]>
Reviewed-by: Greg Kurz <[email protected]>
Tested-by: Greg Kurz <[email protected]>
Reviewed-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>