Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/danube'
  - Checking if hacked quagga bridge exsists and contiune

    Change-Id: I8983ed687dabba0af2128c0ce06bd53aba22c819
    Signed-off-by: Nikolas Hermanns <nikolas.hermanns@ericsson.com>
    (cherry picked from commit 2bfbe25b1df24d562789faa641c41e9cafec7efa)

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index 6788c3b..ecb8fda 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit 6788c3b0ad67b65c41bbf8bf23a6a97561cf6e3a
+Subproject commit ecb8fdae0ed86c64e504a47a381aebbaac3e42e4