drm/i915: Rename to GEN8_LEGACY_PDPES

In gen8, 32b PPGTT has always had one "pdp" (it doesn't actually have
one, but it resembles having one). The #define was confusing as is, and
using "PDPE" is a much better description.

sed -i 's/GEN8_LEGACY_PDPS/GEN8_LEGACY_PDPES/' drivers/gpu/drm/i915/*.[ch]

It also matches the x86 pagetable terminology:
PTE  = Page Table Entry - pagetable level 1 page
PDE  = Page Directory Entry - pagetable level 2 page
PDPE = Page Directory Pointer Entry - pagetable level 3 page

And in the near future (for 48b addressing):
PML4E = Page Map Level 4 Entry

v2: Expanded information about Page Directory/Table nomenclature.

Cc: Daniel Vetter <daniel@ffwll.ch>
CC: Dave Gordon <david.s.gordon@intel.com>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Michel Thierry <michel.thierry@intel.com> (v2)
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 746f77f..58d54bd 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -375,7 +375,7 @@
 	pt_vaddr = NULL;
 
 	for_each_sg_page(pages->sgl, &sg_iter, pages->nents, 0) {
-		if (WARN_ON(pdpe >= GEN8_LEGACY_PDPS))
+		if (WARN_ON(pdpe >= GEN8_LEGACY_PDPES))
 			break;
 
 		if (pt_vaddr == NULL)
@@ -486,7 +486,7 @@
 static int gen8_ppgtt_allocate_page_tables(struct i915_hw_ppgtt *ppgtt,
 					   const int max_pdp)
 {
-	struct page **pt_pages[GEN8_LEGACY_PDPS];
+	struct page **pt_pages[GEN8_LEGACY_PDPES];
 	int i, ret;
 
 	for (i = 0; i < max_pdp; i++) {
@@ -537,7 +537,7 @@
 		return -ENOMEM;
 
 	ppgtt->num_pd_pages = 1 << get_order(max_pdp << PAGE_SHIFT);
-	BUG_ON(ppgtt->num_pd_pages > GEN8_LEGACY_PDPS);
+	BUG_ON(ppgtt->num_pd_pages > GEN8_LEGACY_PDPES);
 
 	return 0;
 }