Update git submodules

Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Set nova disk cachemodes to file directsync

    Set nova/libvirt disk cache modes to file directsync to bypass the
    host page cache & prevent instance's kernel panic due to absent
    /dev partition. Caching mode directsync effectively turns all guest
    I/O operations into direct I/O operations on the host, which is the
    NFS client (virtuals) or GlusterFS (baremetals).
    Also return back to hwe kernel as a golden mean between GA & Edge ones.

    Change-Id: I51ab7d0ee71c214ff16b756cfee16e918738b6fd
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>