Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Move the comment above the config parameter line to avoid the expection

    Traceback (most recent call last):
    File "/opt/nsb_bin/yardstick_venv/lib/python2.7/site-packages/yardstick-0.1.dev0-py2.7.egg/yardstick/cmd/commands/task.py", line 54, in do_start
    result = Task().start(param, **kwargs)
    File "/opt/nsb_bin/yardstick_venv/lib/python2.7/site-packages/yardstick-0.1.dev0-py2.7.egg/yardstick/benchmark/core/task.py", line 148, in start
    self._do_output(output_config, result)
    File "/opt/nsb_bin/yardstick_venv/lib/python2.7/site-packages/yardstick-0.1.dev0-py2.7.egg/yardstick/benchmark/core/task.py", line 227, in _do_output
    dispatchers = DispatcherBase.get(output_config)
    File "/opt/nsb_bin/yardstick_venv/lib/python2.7/site-packages/yardstick-0.1.dev0-py2.7.egg/yardstick/dispatcher/base.py", line 46, in get
    for out_type in config['DEFAULT']['dispatcher']]
    File "/opt/nsb_bin/yardstick_venv/lib/python2.7/site-packages/yardstick-0.1.dev0-py2.7.egg/yardstick/dispatcher/base.py", line 38, in get_cls
    raise RuntimeError("No such dispatcher_type %s" % dispatcher_type)
    RuntimeError: No such dispatcher_type Http # setup multiple dipatcher with comma deperted e.g. file

    Change-Id: I497d0d9ce7fdb7ea2913af6ebeb4bb9008344fed
    Signed-off-by: Deepak S <deepak.s@linux.intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index c2f99db..1857c4f 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit c2f99db8b4d8f021b29a4e3aae483ba715936a66
+Subproject commit 1857c4f37c9d371ddd48eb4d97a379c7c81c18e7