drm/nouveau: remove implicit mapping of every bo into chan_vm

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nouveau_vm.h b/drivers/gpu/drm/nouveau/nouveau_vm.h
index 07d07ff..579ca8c 100644
--- a/drivers/gpu/drm/nouveau/nouveau_vm.h
+++ b/drivers/gpu/drm/nouveau/nouveau_vm.h
@@ -42,6 +42,7 @@
 
 struct nouveau_vma {
 	struct list_head head;
+	int refcount;
 	struct nouveau_vm *vm;
 	struct nouveau_mm_node *node;
 	u64 offset;