Update git submodules

* Update docs/submodules/yardstick from branch 'stable/danube'
  - Merge "cachestat: use raw strings to escape \d" into stable/danube
  - cachestat: use raw strings to escape \d

    Change-Id: Iff40f7c938af0d7c148c708eed19095b140ccb8b
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>
    (cherry picked from commit 6bdf476e43200fefb09a11ea1f6312ca8735fd52)

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index fae70e0..057a75f 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit fae70e08d91ff09b175098ef2f0fdef894bbb138
+Subproject commit 057a75ffb04deb5bf7baf858990b125c525e58f7