Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - [Bug fix] Execute teardown if SLA is set to "assert"

    In Duration runner if SLA is set to "assert" and a SLAValidationError
    happens then a teardown is needed to avoid garbages in the environment.

    JIRA: YARDSTICK-1291

    Change-Id: I9056b0da3e7e496171ed42430ffc340b5c68f108
    Signed-off-by: Dimitrios Markou <mardim@intracom-telecom.com>
    (cherry picked from commit 30fc9f545d526fdbd69af483b0bad0ea781d648c)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index a996133..5821098 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit a99613376daa0656bcd0b24d9c56661ff15c8916
+Subproject commit 5821098118bb97ce9d1a302bb8f19b615ebb01cd