Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Update NSBPerf CLI to adapt to new output format"
  - Update NSBPerf CLI to adapt to new output format

    Change-Id: I1d928857c320e4b8ca326f60b419e7b339599ce1
    Signed-off-by: Deepak S <deepak.s@linux.intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 355601a..7397f29 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 355601ab1b2335550905574148b097292f214325
+Subproject commit 7397f294a448223f8db31404e2d0294065f6f246