Update git submodules

* Update docs/submodules/dovetail from branch 'master'
  - delete unused dashboard backend packages

    JIRA: DOVETAIL-452

    since testapi/mongoDB/openstack 3rd paty dahsboard packages
    are used for dovetail now in releng repo. the out-dated mysql-based
    dashboard backend packages are deleted

    Change-Id: I304c6c40b47e2fac513dd2de873644b749c3275d
    Signed-off-by: MatthewLi <matthew.lijun@huawei.com>

diff --git a/docs/submodules/dovetail b/docs/submodules/dovetail
index 2a4e39e..cbf8b9e 160000 (submodule)
--- a/docs/submodules/dovetail
+++ b/docs/submodules/dovetail
@@ -1 +1 @@
-Subproject commit 2a4e39ee4abdbbadf1285a75fb5540a09432b5f4
+Subproject commit cbf8b9e32d57f30fed5a6b1bba971fd530e65520