Update git submodules
* Update docs/submodules/yardstick from branch 'master'
- Merge "ansible image build improvement"
- ansible image build improvement
JIRA: YARDSTICK-879
Add some image build vars
Add automatic image build of nsb
yardstick_image: ansible-playbook -e img_property="normal" -vvv -i inventory.ini build_yardstick_image.yml
nsb_image_build: ansible-playbook -e img_property="nsb" -vvv -i inventory.ini build_yardstick_image.yml
prepare for yardstick image uploading
Change-Id: I9fdf30084511ca9a008df3b53887b06273bbd549
Signed-off-by: Ace Lee <liyin11@huawei.com>