drm/i915: Drop WARN_ON(flags) from ppgtt_bind_vma()

We will call ppgtt_bind_vma() with flags != 0, so the WARN_ON(flags)
is bogus. Kill it.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -1243,8 +1243,6 @@ ppgtt_bind_vma(struct i915_vma *vma,
 	       enum i915_cache_level cache_level,
 	       u32 flags)
 {
-	WARN_ON(flags);
-
 	vma->vm->insert_entries(vma->vm, vma->obj->pages, vma->node.start,
 				cache_level);
 }