virtio: Do not call setup_features twice

setup_features() is called twice, once in virtio_driver constructor and
once in virtio device driver constructor. Doing it in driver constructor
is enough.

Signed-off-by: Asias He <asias@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

drivers/virtio.cc

@@ -45,8 +45,6 @@ virtio_driver::virtio_driver(pci::device& dev)
 
     // Generic init of virtqueues
     probe_virt_queues();
-
-    setup_features();
 }
 
 virtio_driver::~virtio_driver()