Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "use basename to delete yardstick image loop devices"
  - use basename to delete yardstick image loop devices

    the full path probably isn't matching, so just grep
    for the basename

    JIRA: YARDSTICK-1096
    JIRA: YARDSTICK-1054

    Change-Id: I403a7f51310c0856fae0f79d115ba0786b7c417c
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 5f5d073..436ac33 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 5f5d07360188d566b20279e6ebbb1b0acbd8a966
+Subproject commit 436ac337e1986c7e300da1270b803b9d51a32ccb