worker: simplify surface_update_dest()
worker: simplify surface_update_dest()

Acked-by: Frediano Ziglio <55d48b080b2e443e395cde84d2c83b135a4ff48e@redhat.com>

fgouget/spice,fgouget/spice,SPICE/spice,fgouget/spice,SPICE/spice,SPICE/spice,fgouget/spice