drm/i915: Treat an error from i915_vma_instance() as unlikely

When pinning into the global GTT, an error from creating the VMA is
unlikely, so mark it so.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170119192659.31789-4-chris@chris-wilson.co.ukReviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/i915_gem.c

@@ -3688,7 +3688,7 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj,
 	lockdep_assert_held(&obj->base.dev->struct_mutex);
 
 	vma = i915_vma_instance(obj, vm, view);
-	if (IS_ERR(vma))
+	if (unlikely(IS_ERR(vma)))
 		return vma;
 
 	if (i915_vma_misplaced(vma, size, alignment, flags)) {