Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "NSB fixes: docstring, whitespace, etc."
  - NSB fixes: docstring, whitespace, etc.

    remove unused docstring params
    remove whitespace
    fix sudo vnf_build command
    ignore stdout

    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>
    Change-Id: I6fcdbb0ed4bc6b7fc2f557529f5ff9fd960c05e9

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 04ab053..4e27e2b 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 04ab053f3b1f8118178eeb5b89fdf255ac9f8ab1
+Subproject commit 4e27e2bc0770311feac849c4e3aac9c5ffac4f3d