virtio-gpu api: comment feature flags

Add comments to the existing feature flags,
documenting which commands belong to them.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20190410114227.25846-2-kraxel@redhat.com

include/uapi/linux/virtio_gpu.h

@@ -40,8 +40,16 @@
 
 #include <linux/types.h>
 
-#define VIRTIO_GPU_F_VIRGL 0
-#define VIRTIO_GPU_F_EDID  1
+/*
+ * VIRTIO_GPU_CMD_CTX_*
+ * VIRTIO_GPU_CMD_*_3D
+ */
+#define VIRTIO_GPU_F_VIRGL               0
+
+/*
+ * VIRTIO_GPU_CMD_GET_EDID
+ */
+#define VIRTIO_GPU_F_EDID                1
 
 enum virtio_gpu_ctrl_type {
 	VIRTIO_GPU_UNDEFINED = 0,