Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "exec_tests: remove releng clone code"
  - exec_tests: remove releng clone code

    we bind-mount the credentials into the container
    so we don't need to clone releng

    Change-Id: I838745a1470015a693f1801c93b930e8df06ef4b
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index dd57115..eb5b273 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit dd57115618caa299f6dd1eb350b55ecf062ca92e
+Subproject commit eb5b2735fe9907d38fa8f64df1efbe979158d7ec