Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Override tempest_conf.yaml in ci jobs

    It also removes STORAGE_PROTOCOL (env var) which was removed.

    Change-Id: Ib0f388f20c52ebf2409d2aca0bcba5c641287b40
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index f7b70b9..e715a83 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit f7b70b906308ed8b098e0823b5f7748e084b3cbd
+Subproject commit e715a8309122c3fa3b4983cfa53c82519dd6ead7