Update git submodules

* Update docs/submodules/sfc from branch 'master'
  - Merge "Switch to os.environ for getting OpenStack env vars"
  - Switch to os.environ for getting OpenStack env vars

    CONST shouldn't be selected to get env vars.
    Now it may raise KeyErrors if env is not well configured.

    Change-Id: I5e3f525640809778c5349fdc1c3796227894d0cd
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/sfc b/docs/submodules/sfc
index 14d4de1..7984531 160000 (submodule)
--- a/docs/submodules/sfc
+++ b/docs/submodules/sfc
@@ -1 +1 @@
-Subproject commit 14d4de1dda0d0c4708c8cb9f5dff4060b628f477
+Subproject commit 798453153332a29e0c06cf856d92e6d45722c5a1