Update git submodules

* Update docs/submodules/sdnvpn from branch 'stable/fraser'
  - update fraser release date

    Change-Id: If38328d7814497e9e213ec6edeff5057584d4601
    Signed-off-by: Periyasamy Palanisamy <periyasamy.palanisamy@ericsson.com>
    (cherry picked from commit 9232531e6cd5a5fc00520f200350f141ed6a013b)

diff --git a/docs/submodules/sdnvpn b/docs/submodules/sdnvpn
index 80186c4..d56cc98 160000 (submodule)
--- a/docs/submodules/sdnvpn
+++ b/docs/submodules/sdnvpn
@@ -1 +1 @@
-Subproject commit 80186c4abd195947c63b058452d0a3c6b61d68cd
+Subproject commit d56cc9831e64559cf97071fd8d8a4798bd3a2346