Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Cleanup pktgen unit tests"
  - Cleanup pktgen unit tests

    * Improve test execution
    * Use common functionality in setUp()
    * Disable logging

    JIRA: YARDSTICK-1238

    Change-Id: I0904bf99f0e151b437d506bf322da83f706dcf8f
    Signed-off-by: Miikka Koistinen <miikka.koistinen@nokia.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index a844802..5e8b885 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit a84480299427f5380d6518069371de47346672c6
+Subproject commit 5e8b885c30a1cc1eda23a6cb608566990e7d145c