Update git submodules

* Update docs/submodules/sfc from branch 'stable/euphrates'
  - Bug fix: Actively disable security on SF port

    JIRA: SFC-114

    Some cases show that it was not enough with the patch:
    https://gerrit.opnfv.org/gerrit/#/c/42801/

    We should explicitely disable security in the SF ports. That can be done
    with a the antispoofing parameter in the vnfd

    Change-Id: Ie20ab961633866f48a4abcc299a62e8c55280088
    Signed-off-by: Manuel Buil <mbuil@suse.com>

diff --git a/docs/submodules/sfc b/docs/submodules/sfc
index 841e264..6e4ba89 160000 (submodule)
--- a/docs/submodules/sfc
+++ b/docs/submodules/sfc
@@ -1 +1 @@
-Subproject commit 841e264b708557b86ea906e24d7728d19ee974ed
+Subproject commit 6e4ba8940d0b31d9c53c89968a146a2c0c64a731