Release the mach_port_t reference held within the OSAsyncReference64 structure.
The reference passed to the subclass IOAsyncMethod, or externalMethod() in the IOExternalMethodArguments.asyncReference field.
A return code.
The OSAsyncReference64 structure passed to async methods holds a reference to the wakeup mach port, which should be released to balance each async method call. Behavior is undefined if these calls are not correctly balanced.