Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Execute ovs-logger cmds with sudo

    In some installers we execute commands as ordinary users
    and that causes problems when we need superuser priviledges.

    Change-Id: I84786e63995990e9d68803ed50879b086b0bd4af
    Signed-off-by: Dimitrios Markou <mardim@intracom-telecom.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index b413226..15d0c60 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit b413226970d1e6193b094c0dbe7870729d0ab7f2
+Subproject commit 15d0c604dddaeb6471e3f1f4529b60e32b479582