drm/i810: don't acces hw regs in lastclose

i810 uses a userspace provided mmio map using the drm core map
infrastructure. By the time we reach lastclose, this is all gone
and our mmio_map pointer points at freed memory. Depending upon
luck that still works, most often it just oopses.

Aside: drm maps aren't refcounted, so userspace can essentially oops
the kernel any time it wants to. Who cares.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i810/i810_dma.c

@@ -222,8 +222,6 @@ static int i810_dma_cleanup(struct drm_device *dev)
 			pci_free_consistent(dev->pdev, PAGE_SIZE,
 					    dev_priv->hw_status_page,
 					    dev_priv->dma_status_page);
-			/* Need to rewrite hardware status page */
-			I810_WRITE(0x02080, 0x1ffff000);
 		}
 		kfree(dev->dev_private);
 		dev->dev_private = NULL;