drm/i915: Really share scratch page

A previous patch had set up the ppgtt and ggtt to use the same scratch
page, but still kept around both pointers. Kill it, it's not needed and
gets in our way for upcoming cleanups.
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -492,7 +492,6 @@ struct i915_hw_ppgtt {
 	struct page **pt_pages;
 	uint32_t pd_offset;
 	dma_addr_t *pt_dma_addr;
-	dma_addr_t scratch_page_dma_addr;
 
 	/* pte functions, mirroring the interface of the global gtt. */
 	void (*clear_range)(struct i915_hw_ppgtt *ppgtt,

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -188,13 +188,14 @@ static void gen6_ppgtt_clear_range(struct i915_hw_ppgtt *ppgtt,
 				   unsigned first_entry,
 				   unsigned num_entries)
 {
+	struct drm_i915_private *dev_priv = ppgtt->dev->dev_private;
 	gen6_gtt_pte_t *pt_vaddr, scratch_pte;
 	unsigned act_pt = first_entry / I915_PPGTT_PT_ENTRIES;
 	unsigned first_pte = first_entry % I915_PPGTT_PT_ENTRIES;
 	unsigned last_pte, i;
 
 	scratch_pte = ppgtt->pte_encode(ppgtt->dev,
-					ppgtt->scratch_page_dma_addr,
+					dev_priv->gtt.scratch_page_dma,
 					I915_CACHE_LLC);
 
 	while (num_entries) {
@@ -351,7 +352,6 @@ static int i915_gem_init_aliasing_ppgtt(struct drm_device *dev)
 		return -ENOMEM;
 
 	ppgtt->dev = dev;
-	ppgtt->scratch_page_dma_addr = dev_priv->gtt.scratch_page_dma;
 
 	if (INTEL_INFO(dev)->gen < 8)
 		ret = gen6_ppgtt_init(ppgtt);