Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - Merge "docs: Update E release notes"
  - docs: Update E release notes

    Release notes were updated with VSPERF additions during Euphrates
    release timeframe.

    Change-Id: I87154036676450065906c6fd8bc6db4604c84260
    Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
    Reviewed-by: Al Morton <acmorton@att.com>
    Reviewed-by: Christian Trautman <ctrautma@redhat.com>
    Reviewed-by: Sridhar Rao <sridhar.rao@spirent.com>
    Reviewed-by: Trevor Cooper <trevor.cooper@intel.com>

diff --git a/docs/submodules/vswitchperf b/docs/submodules/vswitchperf
index 2316473..19e7d13 160000 (submodule)
--- a/docs/submodules/vswitchperf
+++ b/docs/submodules/vswitchperf
@@ -1 +1 @@
-Subproject commit 231647397e9f359c11883e154620eae6b0a2cd15
+Subproject commit 19e7d1368af560ef3df6ac39570b9ecc59d3a05d