[libvirt] doc nits

I noticed the following go by yesterday, but won't have time to address them: Function comment for virConnectDomainEventRegister lacks description of arg freecb Function comment for virNodeDeviceGetName lacks description of the function Function comment for virNodeDeviceGetParent lacks description of the function Function comment for virNodeDeviceNumOfCaps lacks description of the function Function comment for virNodeDeviceNumOfCaps lacks description of the function Missing * in function comment for virDomainMigrateFinish Missing * in function comment for virDomainMigrateFinish2 Missing * in function comment for virDomainMigratePerform Missing * in function comment for virDomainMigratePrepare Missing * in function comment for virDomainMigratePrepare2 Missing * in function comment for virDrvSupportsFeature