Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "remove useless workspace from yardstick"
  - remove useless workspace from yardstick

    There is a img file in this workspace, which consumes lots of disk space when
    CI collects artifacts

    Change-Id: Idef0624832cf2b12de2a63fc85bb65f4986ce0ca
    Signed-off-by: grakiss <grakiss.wanglei@huawei.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index bbdfb0c..0b28855 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit bbdfb0cfaa37c6f7648a33b6dd1946c973cde431
+Subproject commit 0b28855e8cac70528d4b92b622547618b814bfee