Update git submodules

* Update docs/submodules/nfvbench from branch 'master'
  - Add support to use vswitch to handle V2V in PVVP SRIOV scenario

    1. Add support to use vswitch to handle V2V in PVVP SRIOV scenario
    2. Update nfvbenchvm to 0.5:
        (1) Update VPP to 17.10;
        (2) Update DPDK testpmd to 17.08;
        (3) Change kernel to based on longterm lineup;

    Change-Id: I944489579a4cd92d17075e80870bbdb32512a150
    Signed-off-by: Yichen Wang <yicwang@cisco.com>

diff --git a/docs/submodules/nfvbench b/docs/submodules/nfvbench
index 58d63a0..1ce98c7 160000 (submodule)
--- a/docs/submodules/nfvbench
+++ b/docs/submodules/nfvbench
@@ -1 +1 @@
-Subproject commit 58d63a026082a7e3207e409d51e919f959627e56
+Subproject commit 1ce98c7510f810a5ee790523a0dcbf429961adda