[luxembourg] Update references for granduc hardware

    Done by cherry-pick and resetted to avoid 120s error.
    Previous commits:

    * [luxembourg] Update references for granduc hardware (mainly eth2 mac addresses)
    * [luxembourg] Add some missing mac addresses, unfinished, not ready for generation
    * [luxembourg] Initial commit for granduc
    * [luxembourg] Initial commit for oar:generate

Signed-off-by: Sebastien Varrette <Sebastien.Varrette@uni.lu>