Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Remove void return value mocks in rally unit tests

    Change-Id: I369b98fb9120830b1868f438c7da2a039a60d890
    Signed-off-by: Juha Kosonen <juha.kosonen@nokia.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 47c0496..3152429 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 47c049623b07dd563218959ad59c0e027a354836
+Subproject commit 31524290992dad02d5ca1e6b17304bf31b56b7f7