Update git submodules

* Update docs/submodules/sdnvpn from branch 'master'
  - add user variables for quagga configuration

    As per the review https://git.opendaylight.org/gerrit/#/c/66195 in
    ansible-opendaylight role, adding required quagga specific
    user variables to configure OpenDaylight with BGPVPN functionality.

    Change-Id: I78e3389c4624fe92f34da13bde6a03d3f51c9675
    Signed-off-by: Periyasamy Palanisamy <periyasamy.palanisamy@ericsson.com>

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index c2d2043..592ab94 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit c2d2043fe34461b66011b974fc535f703e5fa2de
+Subproject commit 592ab94bcf0e34fb9a7a04492b017caa3dd4e964