Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 7a5fddd061b4573d7e96ad7d6c49f456bb17e988
  - [functest] Disable block migration for Fuel

    Block migration can't be used with shared storage.

    Change-Id: I7a746fd52d1c88be07ecbece4885967c7011afdc
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 7163c9b..7a5fddd 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 7163c9bfac715d9b92fe46ac3272c02f470d13fd
+Subproject commit 7a5fddd061b4573d7e96ad7d6c49f456bb17e988