Update git submodules

Update git submodules

* Update docs/submodules/sfc from branch 'master'
  - Merge "Switch from CONST to CONF"
  - Switch from CONST to CONF

    CONST is not the right Functest object to get config data.
    It also updates the way to get constants as proposed by Functest [1].

    [1] https://gerrit.opnfv.org/gerrit/#/c/52389/

    Depends-On: Ie23c0ef90efc839d60f0f3a9754c58746b1f3a00
    Change-Id: I6cfa832466dcefd737314633d807512e46267a69
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>