Update git submodules

* Update docs/submodules/nfvbench from branch 'master'
  - Update hw requirements

    Change-Id: I7e403ec5a550804b43c685bdbfd70c8bff7a2d70
    Signed-off-by: ahothan <ahothan@cisco.com>

diff --git a/docs/submodules/nfvbench b/docs/submodules/nfvbench
index 8da439b..55409f7 160000 (submodule)
--- a/docs/submodules/nfvbench
+++ b/docs/submodules/nfvbench
@@ -1 +1 @@
-Subproject commit 8da439b932537748d379c7bd3bdf560ef739b203
+Subproject commit 55409f779ba0f05ffca52f6ad31ca5b3575c9b53