Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - Updated project description in user and developer guides.
    Updated info on RFC8204 in developer guide.
    Removed whitespaces causing rst validation failure.

    Change-Id: Ibdefee2d0fea03873bac8aba514b68de1f1e0dbe
    Signed-off-by: Trevor Cooper <trevor.cooper@intel.com>

diff --git a/docs/submodules/vswitchperf b/docs/submodules/vswitchperf
index f655cdd..8ce9980 160000 (submodule)
--- a/docs/submodules/vswitchperf
+++ b/docs/submodules/vswitchperf
@@ -1 +1 @@
-Subproject commit f655cdd4db0fed301339be0ae8a9063807095ba5
+Subproject commit 8ce9980d09ce0f54c93479e074b9c67a7d59b092