Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "Update Dockerfile.aarch64.patch"
  - Update Dockerfile.aarch64.patch

    The docker image was not built for aarch64 due to recent changes in the
    Dockerfile. The updates to the Dockerfile.aarch64.patch are:
    - update docker version to 16.04
    - install dependencies for pyopenssl==17.5.0 (libssl-dev and libffi-dev)

    JIRA: ARMBAND-353

    Change-Id: I915172d4e7ce21b1f5de044b20301b076cb6fe20
    Signed-off-by: Cristina Pauna <cristina.pauna@enea.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index a78ca01..35b0d56 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit a78ca014513be16e01f43ac070ae040403fe44fe
+Subproject commit 35b0d561b96b20042eeb68d70bf4d3268edf08fe