Update git submodules

* Update docs/submodules/sfc from branch 'master'
  - Merge "Switch from CONST to env.get()"
  - Switch from CONST to env.get()

    env.get() ensures that default values are reused if unset.
    It also avoids desynchronization between os.environ and CONST.

    It follows the change "Get properly env vars or their default values"
    [1] applied in Functest.

    It also fixes minor issues on shebangs and takes several pylint rules
    into account in this module:
      - http://pylint-messages.wikidot.com/messages:w0702
      - https://www.python.org/dev/peps/pep-0282/

    [1] https://gerrit.opnfv.org/gerrit/#/c/52221/

    Change-Id: Ia7ad168b2cbbade8ea3890fb95dc01bcdfc50468
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/sfc b/docs/submodules/sfc
index 19765df..ee6b39a 160000 (submodule)
--- a/docs/submodules/sfc
+++ b/docs/submodules/sfc
@@ -1 +1 @@
-Subproject commit 19765df464011c3aa895dac67d36360e2834bbf8
+Subproject commit ee6b39aceec72cde4b758b6bd5ea7bab605fb8ed