Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "KVMFORNFV: To avoid livemigration result update to json"
  - KVMFORNFV: To avoid livemigration result update to json

    This patch is used to remove the livemigration testcase result loaded
    to json as there is no dashboard implemented for the testcase

    Change-Id: I7a9589a0bbc5f2a28587c2878da042fc50af18e0
    Signed-off-by: Navya Bathula <navyax.bathula@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 255d5a5..923aa17 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 255d5a579ce0ce4acabd971b94f36fe288fe7489
+Subproject commit 923aa1738cbf5a8053e77e00937fc26f2142f6a3