Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - Changes index depth

    Change-Id: I9f83b22eebb61de7ab98040bd67f7dd7f3caf129
    Signed-off-by: Trevor Cooper <trevor.cooper@intel.com>

diff --git a/docs/submodules/vswitchperf b/docs/submodules/vswitchperf
index 46bf1f2..bd48599 160000 (submodule)
--- a/docs/submodules/vswitchperf
+++ b/docs/submodules/vswitchperf
@@ -1 +1 @@
-Subproject commit 46bf1f20870e4942538a616cc639aa6cfd952145
+Subproject commit bd4859904037d5259d36d7689d464864bad5c395