Update git submodules

* Update docs/submodules/nfvbench from branch 'master'
  - [NFVBENCH-76] REST API remains in running state in case of exception

    catch the exception if result key is missing

    Change-Id: Id212497bb760b835b542afd11ffbe149bc3d46e7
    Signed-off-by: ahothan <ahothan@cisco.com>

diff --git a/docs/submodules/nfvbench b/docs/submodules/nfvbench
index ad043db..42b8c6b 160000 (submodule)
--- a/docs/submodules/nfvbench
+++ b/docs/submodules/nfvbench
@@ -1 +1 @@
-Subproject commit ad043dbc66865d79d78e5d0954c4b2eea32edecd
+Subproject commit 42b8c6bee8e2f64c53b86ceba76210645b10da69