Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "NFVi Test stops after one hour even if configured context duration is longer"
  - NFVi Test stops after one hour even if configured context duration is longer

    JIRA: YARDSTICK-1021

    If the Test is to take longer than the Default Duration timer use
    defined test time.
    If not use Default Duration time

    Change-Id: Idacc188e199ff031310b9826238b63ed3f2ea409
    Signed-off-by: Daniel Martin Buckley <daniel.m.buckley@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 0c455af..d5a2c20 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 0c455af95a0f2258401b54cbca0d84732433fb24
+Subproject commit d5a2c20d8de2796b2d2e2143ddfb2ba839a0e999