drm/nouveau: make fifo.create_context() responsible for mapping control regs

The regs belong to PFIFO, they're different for pretty much the same
generations we need different PFIFO control for, and NVC0 is going
to be even more different than the rest.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nv40_fifo.c b/drivers/gpu/drm/nouveau/nv40_fifo.c
index f6b3580..c86e4d4 100644
--- a/drivers/gpu/drm/nouveau/nv40_fifo.c
+++ b/drivers/gpu/drm/nouveau/nv40_fifo.c
@@ -47,6 +47,11 @@
 	if (ret)
 		return ret;
 
+	chan->user = ioremap(pci_resource_start(dev->pdev, 0) +
+			     NV40_USER(chan->id), PAGE_SIZE);
+	if (!chan->user)
+		return -ENOMEM;
+
 	spin_lock_irqsave(&dev_priv->context_switch_lock, flags);
 
 	nv_wi32(dev, fc +  0, chan->pushbuf_base);