Refactor cifs helper for generic driver

Was:
- writing own local config
- copying local config to remote server
- restart of samba on remote server
- used locks by each server to avoid collision when
  service restarted and config changed

Become:
- used "net conf" command to configure samba
- locks removed as redundant because new approach is collision-proof
- config is not changed directly anymore, so removed all stuff
  related to config change

Change-Id: I51ae6ba17b8b41c4e6daeb328a5f7076673f9a1c