Update git submodules

* Update docs/submodules/samplevnf from branch 'master'
  - Merge "[l2l3 stack] implements new nd state machine & nd buffering"
  - [l2l3 stack] implements new nd state machine & nd buffering

    JIRA: SAMPLEVNF-32

    This patch implements
      ~New nd state machine implementing new states
       like INCOMPLETE, COMPLETE, PROBE, STALE.
      ~Implementing nd buffering, when nd is unresolved.
      ~Integratig the new changes with vCGNAPT
      ~Integrating the new changes with vACL
      ~Integrating the new changes with vFW.
      ~Adding locks to synchronize against multiple VNF threads

    Change-Id: Iaee4f4599ca3016ebb50ee2d9133fd8c39c5cd04
    Signed-off-by: Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index 5175915..d923180 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit 51759157a499326cfe69ec0eecb00b1c5879bf50
+Subproject commit d923180e4af2612361dd7d4bf1627092a4d552d8