drm/i915: Drop get/put_pages for scratch page

While discussing/reviewing __GFP_MOVEABLE behaviour and interactions
with our various page allocations on irc Chris brought up that the
scratch page isn't allocated as moveable, but we still grab/put a
reference to lock it in place. Which is unecessary.

So drop that.
Acked-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -1752,7 +1752,6 @@ static int setup_scratch_page(struct drm_device *dev)
 	page = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);
 	if (page == NULL)
 		return -ENOMEM;
-	get_page(page);
 	set_pages_uc(page, 1);
 
 #ifdef CONFIG_INTEL_IOMMU
@@ -1777,7 +1776,6 @@ static void teardown_scratch_page(struct drm_device *dev)
 	set_pages_wb(page, 1);
 	pci_unmap_page(dev->pdev, dev_priv->gtt.base.scratch.addr,
 		       PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
-	put_page(page);
 	__free_page(page);
 }