drm/i915: remove 512GB allocation warning

Now that we have selftests in place exercising truly huge allocations
we will start to hit the 512GB warning, so now seems like a good time to
remove this user-triggerable WARN.

Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1486047300-13198-1-git-send-email-matthew.auld@intel.com
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -1423,10 +1423,6 @@ static int gen8_alloc_va_range_4lvl(struct i915_address_space *vm,
 	if (ret)
 		return ret;
 
-	WARN(bitmap_weight(new_pdps, GEN8_PML4ES_PER_PML4) > 2,
-	     "The allocation has spanned more than 512GB. "
-	     "It is highly likely this is incorrect.");
-
 	gen8_for_each_pml4e(pdp, pml4, start, length, pml4e) {
 		WARN_ON(!pdp);