Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Add NSB PROX Baremetal dashboard for L3"
  - Add NSB PROX Baremetal dashboard for L3

    JIRA: YARDSTICK-1213

    Change-Id: Id96edc5d23d3530110466e1cf69327c3e267e4c0
    Signed-off-by: Xavier Simonart <xavier.simonart@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index e07163f..f52ffab 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit e07163f9d5ef6060112792caf08678943dc2fe11
+Subproject commit f52ffab5e25a768a180644ecfe82caabb54df9ad