Updated git submodules

Project: releng/builder master 5666ae22f8f5f344679a4863cd2072138f3653d6

Install mininet 2.2.1

We get build failures with mininet 2.2.2 because it's not a valid git
tag in github for the project. Revert back to 2.2.1 as it's the closest
next thing.

Change-Id: Ie18f8be125fbc7a7972acf66fced91c640353c33
Signed-off-by: Thanh Ha <thanh.ha@linuxfoundation.org>

diff --git a/docs/submodules/releng/builder b/docs/submodules/releng/builder
index 6094bd7eb98ff24348699c73c31c3ce331b0929a..5666ae22f8f5f344679a4863cd2072138f3653d6 160000 (submodule)
--- a/docs/submodules/releng/builder
+++ b/docs/submodules/releng/builder
@@ -1 +1 @@
-Subproject commit 6094bd7eb98ff24348699c73c31c3ce331b0929a
+Subproject commit 5666ae22f8f5f344679a4863cd2072138f3653d6