drm/nouveau/fifo: turn all fifo modules into engine modules

Been tested on each major revision that's relevant here, but I'm sure there
are still bugs waiting to be ironed out.

This is a *very* invasive change.

There's a couple of pieces left that I don't like much (eg. other engines
using fifo_priv for the channel count), but that's an artefact of there
being a master channel list still.  This is changing, slowly.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nv20_graph.c b/drivers/gpu/drm/nouveau/nv20_graph.c
index 385e2b4..e34ea30 100644
--- a/drivers/gpu/drm/nouveau/nv20_graph.c
+++ b/drivers/gpu/drm/nouveau/nv20_graph.c
@@ -43,8 +43,6 @@
 int
 nv20_graph_unload_context(struct drm_device *dev)
 {
-	struct drm_nouveau_private *dev_priv = dev->dev_private;
-	struct nouveau_fifo_engine *pfifo = &dev_priv->engine.fifo;
 	struct nouveau_channel *chan;
 	struct nouveau_gpuobj *grctx;
 	u32 tmp;
@@ -62,7 +60,7 @@
 
 	nv_wr32(dev, NV10_PGRAPH_CTX_CONTROL, 0x10000000);
 	tmp  = nv_rd32(dev, NV10_PGRAPH_CTX_USER) & 0x00ffffff;
-	tmp |= (pfifo->channels - 1) << 24;
+	tmp |= 31 << 24;
 	nv_wr32(dev, NV10_PGRAPH_CTX_USER, tmp);
 	return 0;
 }