Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - xena_duration_fix: Revert xena continuous to port time limits

    Revert xena continuous traffic to port based time limits as
    packet limits have an uppers bounds which could be reached
    with small packet sizes and longer durations.

    JIRA: VSPERF-507

    Change-Id: I56986159643344f7872e311590f7d05ac02b038b
    Signed-off-by: Christian Trautman <ctrautma@redhat.com>

diff --git a/docs/submodules/vswitchperf b/docs/submodules/vswitchperf
index 0498b5f..ced349e 160000 (submodule)
--- a/docs/submodules/vswitchperf
+++ b/docs/submodules/vswitchperf
@@ -1 +1 @@
-Subproject commit 0498b5fb3893e4331191808e3501d00b684af9b4
+Subproject commit ced349e749efcd129943544812bc607238879383