Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Update load_images.sh to MCP@aarch64

    The load_images.sh script still contained old functionality.
    The changes are:
    - don't use TestVM anymore, MCP does not load that by default like Fuel did
      upload the cirros image instead
    - don't upload the kernel separately for aarch64, one part image works now
    - add the needed extra-properties accordingly to each image

    The script was tested on arm, the test are running now without errors

    JIRA: ARMBAND-285

    Change-Id: Iee8ce6cde43bebceb2edbb1310ea81c665876aff
    Signed-off-by: Cristina Pauna <cristina.pauna@enea.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index a7c3814..af71c46 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit a7c381437eadec0a7ccb694a6b9461f4f03c1484
+Subproject commit af71c468fe83a5149e0e18cdb233e059302209e3