Update git submodules

* Update docs/submodules/sfc from branch 'master'
  - Update CMD in gating Dockerfile

    It conforms with the change "Remove prepare_env" [1].

    [1] https://gerrit.opnfv.org/gerrit/#/c/47267/

    Change-Id: I9a80049e002b812d097067dc53798fa3bc532505
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/sfc b/docs/submodules/sfc
index b5e4dd9..f1304ee 160000 (submodule)
--- a/docs/submodules/sfc
+++ b/docs/submodules/sfc
@@ -1 +1 @@
-Subproject commit b5e4dd95cd0d4c147aaaac90dd421560d809a67c
+Subproject commit f1304eec7ac5997868ba7eae53a1da7e0c90679b