drm/i915/selftests: Fix inconsistent IS_ERR and PTR_ERR

Fix inconsistent IS_ERR and PTR_ERR in i915_gem_dmabuf.c
Signed-off-by: Kai Song <songkai01@inspur.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211022120655.22173-1-songkai01@inspur.com

drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c

@@ -102,7 +102,7 @@ static int igt_dmabuf_import_same_driver_lmem(void *arg)
 	obj = __i915_gem_object_create_user(i915, PAGE_SIZE, &lmem, 1);
 	if (IS_ERR(obj)) {
 		pr_err("__i915_gem_object_create_user failed with err=%ld\n",
-		       PTR_ERR(dmabuf));
+		       PTR_ERR(obj));
 		err = PTR_ERR(obj);
 		goto out_ret;
 	}
@@ -158,7 +158,7 @@ static int igt_dmabuf_import_same_driver(struct drm_i915_private *i915,
 					    regions, num_regions);
 	if (IS_ERR(obj)) {
 		pr_err("__i915_gem_object_create_user failed with err=%ld\n",
-		       PTR_ERR(dmabuf));
+		       PTR_ERR(obj));
 		err = PTR_ERR(obj);
 		goto out_ret;
 	}