Update git submodules

* Update docs/submodules/samplevnf from branch 'master'
  - l2l3_stack: Remove the build folder from l2l3_stack

    JIRA: SAMPLEVNF-47

    The intermediate files and build directory will be regenerated
    at build time. These files/folder are not required.

    Change-Id: Iabf50c8dfcf80d9d6f4db0fca9a5a84e3fc6447a
    Signed-off-by: Anand B Jyoti <anand.b.jyoti@intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index b835128..156e2f1 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit b8351286a53658bee2471430aaafac4eb72bdfde
+Subproject commit 156e2f1781bf3d30ecd54df4c22b23944c85eed1