Update git submodules

* Update docs/submodules/ipv6 from branch 'stable/euphrates'
  - Update ODL Carbon status

    Updated ODL Carbon status by indicating deprecated old-netvirt

    Change-Id: I480788e6ef6ff3ba801651e4aa37ea4ab5929833
    Signed-off-by: Bin Hu <bh526r@att.com>
    (cherry picked from commit e7045e051d8500a2e3b4f2bebbf61e2511c5106a)

diff --git a/docs/submodules/ipv6 b/docs/submodules/ipv6
index f9aeee1..d510a1c 160000 (submodule)
--- a/docs/submodules/ipv6
+++ b/docs/submodules/ipv6
@@ -1 +1 @@
-Subproject commit f9aeee14fd64491eaae522c16e87ba015da0eb9a
+Subproject commit d510a1caf37af72cdd416ad177b1ec5f17fc1a1a