drm/qxl: remove XXX comment from the UAPI header

One cannot rename the struct at this point, so might as well remove the
comment.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

include/uapi/drm/qxl_drm.h

@@ -84,7 +84,6 @@ struct drm_qxl_command {
 	__u32                pad;
 };
 
-/* XXX: call it drm_qxl_commands? */
 struct drm_qxl_execbuffer {
 	__u32		flags;		/* for future use */
 	__u32		commands_num;