drm/nouveau/bar: tidy up the subdev and object class definitions

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/core/engine/fifo/nvc0.c b/drivers/gpu/drm/nouveau/core/engine/fifo/nvc0.c
index 9ac94d4..b22a33f 100644
--- a/drivers/gpu/drm/nouveau/core/engine/fifo/nvc0.c
+++ b/drivers/gpu/drm/nouveau/core/engine/fifo/nvc0.c
@@ -33,6 +33,7 @@
 
 #include <subdev/timer.h>
 #include <subdev/bar.h>
+#include <subdev/fb.h>
 #include <subdev/vm.h>
 
 #include <engine/dmaobj.h>