Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Merge "Remove __init__ method overriding in HeatContextTestCase" into stable/fraser
  - Remove __init__ method overriding in HeatContextTestCase

    Unit test case clases should implement setUp() method instead of overriding
    __init__() method.

    JIRA: YARDSTICK-1210

    Change-Id: I0f9a10575f9aeebf76dfa84619e59589b3ea83f6
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>
    (cherry picked from commit 619bed631f064a94ab20ac296802d467ebe32318)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 6ad50ee..0af2b92 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 6ad50ee62571c9a860a728022a6c892b56fb0511
+Subproject commit 0af2b92e25345ec15649424d786142ea126e66ac