Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Verify the route list before parsing the data key"
  - Verify the route list before parsing the data key

    Exception:
    line 502, in get_route_data
    return next((route[data_key] for route in route_list if route['if'] ==
    port), None)
    TypeError: 'NoneType' object is not iterable

    Change-Id: Ia45d90a4e9a61cb917b23efd03b86eafb249b747
    Signed-off-by: Deepak S <deepak.s@linux.intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 641b528..9c6eba1 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 641b52820afd1c61261cda954803cc335b818ccc
+Subproject commit 9c6eba101c7b656d077b95cf5d028551b0460aa1