Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Create 2 images and flavors for tempest tests"
  - Create 2 images and flavors for tempest tests

    Also
    1. remove the obsolete function: generate_test_accounts_file
    2. Use patch mechanism to get config

    Change-Id: I455ac37de71519bcaf9a51e5f1de1b9bc83b9ba6
    Signed-off-by: Linda Wang <wangwulin@huawei.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 09e3ded..a51e1ca 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 09e3dedbb5807bc1223553f57a87696f51c83e99
+Subproject commit a51e1ca848bd3044e928855650eef4dd4bbaced4