Update git submodules

* Update docs/submodules/samplevnf from branch 'master'
  - Add support for multiple tasks generating to same ip in l3 mode.

    When multiple tasks generate to the same ip in l3 mode (i.e. with arp
    support), all those tasks generate arp requests. we need to make sure
    that they all receive a arp-reply i.e. that the master broadcast
    the reply to all those cores.

    Change-Id: I7e89196497a1016a94dde167f212b1f6ed03bcfe
    Signed-off-by: Xavier Simonart <xavier.simonart@intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index 65504ce..516310e 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit 65504ce40edc1a2f5ad154ed7935d93a3650e5b7
+Subproject commit 516310e780f11d844bc06e5fafb60938e329c651