Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Fix inventory.ini for build_yardstick_image"
  - Fix inventory.ini for build_yardstick_image

    In [1], 'no hosts matched' occured because 'jumphost' was not defined
    in inventory.ini.

    [1]: https://build.opnfv.org/ci/job/yardstick-daisy-baremetal-daily-master/72/console

    Change-Id: I8cb36bf083ce589e94f5f8b115e99556f0bcb053
    Signed-off-by: Alex Yang <yangyang1@zte.com.cn>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 6d7314e..753e8ad 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 6d7314e986c6359b59198d155a7baa31891e888f
+Subproject commit 753e8ad700f602c9b2804f212376d0ad8b14ca6d