Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Enable intel_pmu plugin in collectd

    Change-Id: I62c6416e5c79d0b90880985bb5c076b65e34192e
    Signed-off-by: Deepak S <deepak.s@linux.intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 07644db..4967785 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 07644db4910643d6f6705c6a12c5ec612a99a33a
+Subproject commit 49677852f2bc690d235318d2208504241eef61a9