Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Update to Xtesting 0.57

    It protects vs unset POD_ARCH (It completes "Disable Vmtp if POD_ARCH
    = aarch64" [1])

    [1] https://gerrit.opnfv.org/gerrit/#/c/60927/

    Change-Id: I343c7a9047fe09aad7b9a39d0d045ac709f07a7a
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
  - Remove all lxd refs

    All Joid runs are stopped, then these scenarios can't be maintained.

    Change-Id: Ida7c8c86cbd377024047d4abbbc1806ad65afc8a
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>