Update git submodules

* Update docs/submodules/yardstick from branch 'stable/gambia'
  - Merge "Update Multi Port Stats reading for PROX" into stable/gambia
  - Update Multi Port Stats reading for PROX

    JIRA: YARDSTICK-1458

    Removed excessive jitter by removing extra sleeps in start/stop/reset
      ssh
    Removed extra retries when bad data returned
    Added a slep at end of test to give runner a chance to empty the queue
      on shutdown
    Added a timeout on port retry attempts

    Change-Id: Ica60b11c7af242817a83c154157827581f60d16a
    Signed-off-by: Daniel Martin Buckley <daniel.m.buckley@intel.com>
    (cherry picked from commit b2fd601c33e3322ccc9e675242f091dba2eeb644)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 64f3460..528234b 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 64f3460a95a837b4f0f4181eee1891b50d3ccc58
+Subproject commit 528234b9906fb0791b7fc2b398e17bc67204aebb