drm/i915/selftests: Drop stale struct_mutex

	struct intel_engine_cs *engine;

	struct i915_gem_context *ctx;

	enum intel_engine_id id;

	intel_wakeref_t wakeref;

	struct igt_spinner spin;

	int err = -ENOMEM;

	 * on the same engine from the same parent context.

	 */

	mutex_lock(&i915->drm.struct_mutex);

	wakeref = intel_runtime_pm_get(&i915->runtime_pm);

	if (igt_spinner_init(&spin, &i915->gt))

		goto err_unlock;

		return err;

	ctx = kernel_context(i915);

	if (!ctx)

	kernel_context_close(ctx);

err_spin:

	igt_spinner_fini(&spin);

err_unlock:

	intel_runtime_pm_put(&i915->runtime_pm, wakeref);

	mutex_unlock(&i915->drm.struct_mutex);

	return err;

}