Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Merge "NSB Topology fix for Prox 4 port test case" into stable/fraser
  - NSB Topology fix for Prox 4 port test case

    The uplink and downlink interfaces for the 4 port
    test cases were inconsistent and fixed in this commit.

    This affects all the 4 port PROX test cases.

    Tested on: Heat L2fwd-4 and L3fwd-4 test case.

    JIRA: YARDSTICK-1185

    Change-Id: Ia2ce7ed0dc395b812f84ede94e259b42dc833579
    Signed-off-by:Abhijit Sinha <abhijit.sinha@intel.com>
    (cherry picked from commit 8ebd2d3fde473ffcd139090bd688882d4e5e0f44)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index b771798..ba78ba9 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit b77179801b1af246e2b099919f8618c110408b9f
+Subproject commit ba78ba90ee81e1138de2252f769453f45dde16fe