Although not strictly required, it is nice to have vhost_log_put()
safely callable multiple times.
Clear dev->log* when calling vhost_log_put() to make the function
idempotent. This also simplifies a bit the caller work.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>