Update git submodules

* Update docs/submodules/samplevnf from branch 'stable/euphrates'
  - common: Changes to common code for gateway support

    JIRA: SAMPLEVNF-58

    Common code changes for gateway packet forwarding.

    Change-Id: Ie002c94b8febab9c0923e1bb261e5ea931cd4712
    Signed-off-by: Anand B Jyoti <anand.b.jyoti@intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index a12bf49..6c01f30 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit a12bf49777c66b03354d30b66be301167a86be94
+Subproject commit 6c01f3018228e2920d26235079ee40bd8a88f5b7