Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Stop time.sleep mocks in unit tests

    tVpeApproxVnf and TestProxSocketHelper classes mock "time.sleep" in
    the setUp method without deleting it at the end of the test execution.

    JIRA: YARDSTICK-1243

    Change-Id: Iff31d9c7b400ad8a47f37792aeb0d20328b9d9e1
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index a3399d0..9b22f5b 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit a3399d07b83ce0e50d9c0144d00a7ba83a73390f
+Subproject commit 9b22f5b23050a0be67f8237e4d0b412f58b43472