Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Use context name instead of key_uuid"
  - Use context name instead of key_uuid

    context.key_uuid is only used as a suffix for the key files.
    There is already a unique ID associated with a the context;
    the context name includes a task ID, which is a UUID.

    This patch sets context.key_uuid to to context.name instead of
    generating a separate UUID

    As a result, get_short_key_uuid() is not needed.

    JIRA: YARDSTICK-1028
    Change-Id: Id175061d6cfe23a068bb3d12ce176c1f176e8236
    Signed-off-by: Emma Foley <emma.l.foley@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 0b34073..de8ce98 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 0b340735f2a37b9a05d3d86f79aa706b3e43bb5d
+Subproject commit de8ce9889cfc9e9d62e26e53b5f27b2f4cd9ff06