Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "Update opendaylight/neutron patch"
  - Update opendaylight/neutron patch

    Align opendaylight support patch with latest neutron formula.
    Employ native ML2 backend/engine option as is instead of bringing
    in the "opendaylight" keyword into reclass model.
    Unfreeze the maas & neutron formulas versions.

    Change-Id: I2807dcf9f83b01d453bca6453524f840c378972f
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 6692c89..637ab12 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 6692c895ba7df012fce4ee1f54f6450e2f13c950
+Subproject commit 637ab12768237d45a37f3c41716d36d3de53821d