ifup: <match> recursive <child> generation
fsm: change ni_fsm_exists_applicable_policy param
fsm: check only given worker's name on <device>
fsm: cleanup of ni_fsm_policy_applicable()

- move common checks to the caller
- removed unnecessary debug messages
- cleanup comments
nanny: cleanup of apply policy functions

- ni_factory_device_apply_policy()
  Do not generate config. Config must be already
  generated (fail otherwise)
- ni_managed_device_apply_policy()
  Generate config from policy only when not already
  done.