Update git submodules

* Update docs/submodules/yardstick from branch 'stable/danube'
  - yardstick env influxdb/grafana cmd support centos

    JIRA: YARDSTICK-714

    Currently yardstick env influxdb/grafana command do not support centos.
    Because we use the gateway ip to get the service of influxdb and grafana.
    But in centos, we can not access influxdb/grafana service via gateway ip.
    In this patch, I use docker inspect to get the ip of influxdb and grafana.
    So these command can support centos.

    Change-Id: I4599cbbd0fe43de9cf08e5d9e74d31edbb742998
    Signed-off-by: chenjiankun <chenjiankun1@huawei.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 961de94..cce6fa7 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 961de9447288c431a47a42a31a70df23ccc726eb
+Subproject commit cce6fa7f1bca039bedc7484aff6f7862d9074053