drm/i915/gem: Check the correct variable in selftest

There is a copy and paste bug in this code.  It's supposed to check
"obj2" instead of checking "obj" a second time.

Fixes: 80f0b679 ("drm/i915: Add an implementation for i915_gem_ww_ctx locking, v2.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/8ilneOcJAjwqU4t@mwand
(cherry picked from commit 14f2d760)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/selftests/i915_gem.c

@@ -211,8 +211,8 @@ static int igt_gem_ww_ctx(void *arg)
 		return PTR_ERR(obj);
 
 	obj2 = i915_gem_object_create_internal(i915, PAGE_SIZE);
-	if (IS_ERR(obj)) {
-		err = PTR_ERR(obj);
+	if (IS_ERR(obj2)) {
+		err = PTR_ERR(obj2);
 		goto put1;
 	}