Update git submodules

* Update docs/submodules/samplevnf from branch 'master'
  - Merge "Fix potential crash when shuffling mbufs"
  - Fix potential crash when shuffling mbufs

    Change-Id: I70de6345afc6a696906f006c1b0f44540ae4ecec
    Signed-off-by: Xavier Simonart <xavier.simonart@intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index 997a366..6d005f7 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit 997a3664e7508f5e2b24cb0d105e411bf71e0d60
+Subproject commit 6d005f74525630cd63a759bff8cf2e9ae6b02e88