drm/i915: Kill gtt_end

It's duplicated in the more useful gtt_total.

Reviewed-by: Rodrigo Vivi <[e-mail]>
Signed-off-by: Ben Widawsky <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>

drivers/gpu/drm/i915/i915_drv.h

···
 		/** Usable portion of the GTT for GEM */
 		unsigned long gtt_start;
 		unsigned long gtt_mappable_end;
-		unsigned long gtt_end;
 		unsigned long stolen_base; /* limited to low memory (32-bit) */
 
 		/** "Graphics Stolen Memory" holds the global PTEs */

drivers/gpu/drm/i915/i915_gem_gtt.c

···
 
 	/* First fill our portion of the GTT with scratch pages */
 	i915_ggtt_clear_range(dev, dev_priv->mm.gtt_start / PAGE_SIZE,
-			      (dev_priv->mm.gtt_end - dev_priv->mm.gtt_start) / PAGE_SIZE);
+			      dev_priv->mm.gtt_total / PAGE_SIZE);
 
 	list_for_each_entry(obj, &dev_priv->mm.bound_list, gtt_list) {
 		i915_gem_clflush_object(obj);
···
 
 	dev_priv->mm.gtt_start = start;
 	dev_priv->mm.gtt_mappable_end = mappable_end;
-	dev_priv->mm.gtt_end = end;
 	dev_priv->mm.gtt_total = end - start;
 	dev_priv->mm.mappable_gtt_total = min(end, mappable_end) - start;