Update git submodules

* Update docs/submodules/yardstick from branch 'stable/fraser'
  - Merge "Add active wait function" into stable/fraser
  - Add active wait function

    Added function "wait_until_true". This function will make an active
    wait until the predicate passed as an argument returns True.

    If the timeout expires, the function will raise a generic exception
    or a user defined one passed as an argument.

    This function will be used in YARDSTICK-1127.

    JIRA: YARDSTICK-1128

    Change-Id: I9854e465ac6b586bf4be39ab4b266d5625b39e30
    Signed-off-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>
    (cherry picked from 099108aab37d1fae1b27f4e2e20136c234df1a52)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 535780e..2190402 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 535780e99a4e76311a7da3df75715211d0dca6d4
+Subproject commit 2190402565343fbc712d5cba936b8d7d6dba56b4