Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - cgnat: duplicate keys are not allowed

    the current ConfigParser does not handle duplicate keys
    in ini files.

    Change-Id: Iaafbbab740a809a59edfd93c84d0029ef10ac6f3
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 19e0c4d..eab7e0f 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 19e0c4d2e004e18e6f5687e420dc51a4032b06c2
+Subproject commit eab7e0f4b1ffb895a93107ab28b26ceb3b084e99