virtio: Rename set_features to finalize_features

Rather than explicitly handing the features to the lower-level, we just
hand the virtio_device and have it set the features.  This make it clear
that it has the chance to manipulate the features of the device at this
point (and that all feature negotiation is already done).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 5a30cfb..bf8ec28 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -61,9 +61,10 @@
  * @get_features: get the array of feature bits for this device.
  *	vdev: the virtio_device
  *	Returns the first 32 feature bits (all we currently need).
- * @set_features: confirm what device features we'll be using.
+ * @finalize_features: confirm what device features we'll be using.
  *	vdev: the virtio_device
- *	feature: the first 32 feature bits
+ *	This gives the final feature bits for the device: it can change
+ *	the dev->feature bits if it wants.
  */
 struct virtio_config_ops
 {
@@ -79,7 +80,7 @@
 				     void (*callback)(struct virtqueue *));
 	void (*del_vq)(struct virtqueue *vq);
 	u32 (*get_features)(struct virtio_device *vdev);
-	void (*set_features)(struct virtio_device *vdev, u32 features);
+	void (*finalize_features)(struct virtio_device *vdev);
 };
 
 /* If driver didn't advertise the feature, it will never appear. */