drm/nouveau/fb: merge fb/vram and port to subdev interfaces

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/core/engine/fifo/nv40.c b/drivers/gpu/drm/nouveau/core/engine/fifo/nv40.c
index 3079f08..23ae459 100644
--- a/drivers/gpu/drm/nouveau/core/engine/fifo/nv40.c
+++ b/drivers/gpu/drm/nouveau/core/engine/fifo/nv40.c
@@ -163,7 +163,7 @@
 		break;
 	default:
 		nv_wr32(dev, 0x002230, 0x00000000);
-		nv_wr32(dev, 0x002220, ((dev_priv->vram_size - 512 * 1024 +
+		nv_wr32(dev, 0x002220, ((nvfb_vram_size(dev) - 512 * 1024 +
 					 dev_priv->ramfc->pinst) >> 16) |
 				       0x00030000);
 		break;