drivers: udc_dwc2: Disable endpoints asynchronously

Do not synchronously wait for endpoint interrupt bits when disarming
endpoints. Introduce ep_disabled k_event that makes it possible for
application to wait for the action to take effect which is necessary
when handling SetFeature(ENDPOINT_HALT) or SetInterface() requests.

This change improves incomplete iso IN and OUT handling performance,
especially when there are multiple isochronous endpoints that need
servicing.

Signed-off-by: Tomasz Moń <tomasz.mon@nordicsemi.no>