Fix vmdef usage after domain crash in monitor on device detach

Fix vmdef usage after domain crash in monitor on device detach

https://bugzilla.redhat.com/show_bug.cgi?id=1161024

In the device type-specific functions, exit early
if the domain has disappeared, because the cleanup
should have been done by qemuProcessStop.

Check the return value in processDeviceDeletedEvent
and qemuProcessUpdateDevices.

Skip audit and removing the device from live def because
it has already been cleaned up.