node_device_hal.h: Use #pragma once

Acked-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>

src/node_device/node_device_hal.h

@@ -19,7 +19,4 @@
  *
  */
 
-#ifndef LIBVIRT_NODE_DEVICE_HAL_H
-# define LIBVIRT_NODE_DEVICE_HAL_H
-
-#endif /* LIBVIRT_NODE_DEVICE_HAL_H */
+#pragma once