Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Cleanup TestProxSocketHelper unit tests"
  - Cleanup TestProxSocketHelper unit tests

    Removed unneeded output.

    JIRA: YARDSTICK-1284

    Change-Id: I41d9b8d2df417fa19b0a6f8c13bc9837dc3dde95
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index e783dbb..a7c1d2a 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit e783dbb8efa370578b5b1a135a980c2603d27881
+Subproject commit a7c1d2a9ea76951dbf9ec5e14fa9413156232f4a