Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - ci: Fix of CI graphs generation

    Parameters must be quoted, otherwise list of testcases is split
    among many parameters.

    Change-Id: I16ca4feb7e8d30bbbed60fd259e3bd3155f382b3
    Signed-off-by: Martin Klozik <martinx.klozik@intel.com>

diff --git a/docs/submodules/vswitchperf b/docs/submodules/vswitchperf
index a96c5e8..e668c36 160000 (submodule)
--- a/docs/submodules/vswitchperf
+++ b/docs/submodules/vswitchperf
@@ -1 +1 @@
-Subproject commit a96c5e8bc383302ff700e1f757a6626e529db44c
+Subproject commit e668c362f4dc8589df3899d86f28e7b815a79a85