Method trigger

devices/src/legacy/serial.rs:358–360

(&self, _index: InterruptIndex)

    impl InterruptSourceGroup for TestInterrupt {
        fn trigger(&self, _index: InterruptIndex) -> result::Result<(), std::io::Error> {
            self.event_fd.write(1)
        }
        fn update(
            &self,
            _index: InterruptIndex,