Update git submodules

* Update docs/submodules/samplevnf from branch 'master'
  - Merge "Fix potential crash if link speed is null"
  - Fix potential crash if link speed is null

    Link_speed could be null when prox started with the ports down.
    This was potentially causing a crash.
    Another task will need to update link speed when the port come
    up. Failing to do this results in less accurate latencies
    (no extrapolation)

    Change-Id: I597b68e30117e6edb9ccb4732c2acedd5eb8ac80
    Signed-off-by: Xavier Simonart <xavier.simonart@intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index 2adcda4..a3fc5b6 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit 2adcda4042d4b20a5df956df854b834aa4d9f2dc
+Subproject commit a3fc5b620eec70c9e2c043a66d0b358c29d51106