usb: cdns3: core: fix goto label for error path

The usb_role_switch_register has been already called, so if the
devm_request_irq has failed, it needs to call usb_role_switch_unregister.

Fixes: b1234e3b ("usb: cdns3: add runtime PM support")
Signed-off-by: Peter Chen <peter.chen@nxp.com>