Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Remove checkno.png and checkyes.png due to license issue"
  - Remove checkno.png and checkyes.png due to license issue

    JIRA: YARDSTICK-817

    Since checkno.png and checkyes.png is not Apache-2 license based.
    so we need to remove them.

    Change-Id: I40dd303fb54a3736ca969ac1c186d2cd23408436
    Signed-off-by: chenjiankun <chenjiankun1@huawei.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 2a02457..fecd540 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 2a02457c7b4d43e6a3d9d513023bc312a0a96ba9
+Subproject commit fecd5406d7d192f812ac84bf8093f1c6688eea18