Update git submodules

* Update docs/submodules/samplevnf from branch 'master'
  - Trivial: fix trailing white-spaces

    Makefile checks for some coding style rules.
    Previous commit introduced trailing white-spaces, which broke
    compilation.

    Change-Id: Ia57fc9b1428b4a9f8537dce4875e62ac55265fe3
    Signed-off-by: Patrice Buriez <patrice.buriez@intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index a3fc5b6..37d8126 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit a3fc5b620eec70c9e2c043a66d0b358c29d51106
+Subproject commit 37d81265d5e06c2ad87446511681259222c94984