Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Refactor refstack to limit instructions

    Change-Id: I3cd490d18898d0ee6f48e4c19d7ed65c0cf0c275
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 78c0b09..8de16b7 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 78c0b09a2cf3a57ae5d4f8cfe67ab66ad9d8aef2
+Subproject commit 8de16b7187a8a6133c025ef504ead48d7adb0cac