[libvirt] doc nits

[Jim Meyering]

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