Update git submodules

Update git submodules

* Update docs/submodules/yardstick from branch 'stable/euphrates'
  - pmu: remove event_download_local workaround script

    intel_pmu needs to download a config file based on the
    CPU model.  When generating VNF images we don't have
    access to the actual vCPU that will be used, so we
    can't predownload.  This code was meant to be a fix
    for that by downloading all the configs and then
    selecting one that matched the vCPU.

    However we have license issues with intel_pmu enven GPLv2 code,
    so remove it for now.

    Change-Id: I5257ff7c4ddc1d40537dadb29efa40d1d68cb852
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>
    (cherry picked from commit 7a5c45daa9b146dfc50068165aba5ec6bc2e1e2c)