Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Bug Fix: correct the file path to build docker file

    To be able to build a docker file, the path to file
    "exec_tests.sh" should be modifed from .docker/exec_tests.sh
    to ./exec_tests.sh.

    JIRA: YARDSTICK-1157

    Change-Id: I0f707ba579039d0efc8f2185b596e23b901c09df
    Signed-off-by: ting wu <ting.wu@enea.com>
    (cherry picked from commit e5c9c487105f0bbe6416e612da77f5c93b9b354c)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 266baa2..02f4d1c 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 266baa2694e397e2a449ba15d08046ef5baeab9a
+Subproject commit 02f4d1c0ff5583177cd65d6fc60a116ca109adc8