Update git submodules
* Update docs/submodules/yardstick from branch 'master'
- Merge "Prohibit the importation of a list of libraries"
- Prohibit the importation of a list of libraries
Some modules can't be imported and used in Yardstick. For example,
"ansible" has GPLv3 license and can't be used as a library in this
project without modifying Yardstick license.
JIRA: YARDSTICK-896
Change-Id: I9d6bec0493ac50f1051235cc77e81059dfc3e01c
Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>