platform/chrome: cros_usbpd_logger: null check create_singlethread_workqueue

In cros_usbpd_logger_probe the return value of
create_singlethread_workqueue may be null, it should be checked.

Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>