drm/nv40/mpeg: fix context handling

It slipped in thanks to typeless API.
Signed-off-by: NMarcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/core/engine/mpeg/nv40.c

@@ -38,7 +38,7 @@ struct nv40_mpeg_priv {
 };
 
 struct nv40_mpeg_chan {
-	struct nouveau_mpeg base;
+	struct nouveau_mpeg_chan base;
 };
 
 /*******************************************************************************