Update git submodules

* Update docs/submodules/releng from branch 'master'
  - yardstick: remove apexlake

    apexlake was removed from yardstick codebase

    Change-Id: I8eb826aa725dfb0e2c2c7a0bc1b15931fa245967
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index a00a519..f555ded 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit a00a519229c41e298299d54a14839ebe46ebe40f
+Subproject commit f555dedcc0197e0fd08bbccff2aef72ebb8c0d68