Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "bugfix: Fix duplicate 'address' in standlone SRIOV"
  - bugfix: Fix duplicate 'address' in standlone SRIOV

    * Add unit test per Rodolfo's comment

    Creating a VM using generted xml file /tmp/vm_sriov_0.xml returns
    an XML error: missing source address type.

    This fix modifies generted xml from:
    <source>
    <address>
    <address bus="0x1a" domain="0x0000" function="0x0" slot="0x10" type="pci" />
    </address>
    </source>

    to:

    <source>
    <address bus="0x1a" domain="0x0000" function="0x0" slot="0x10" type="pci" />
    </source>

    Change-Id: I694153e7468986bacb19ba3e09e761993aad7184
    Signed-off-by: Dino Simeon Madarang <dinox.madarang@intel.com>
    Reviewed-by: Rodolfo Alonso Hernandez <rodolfo.alonso.hernandez@intel.com>
    Reviewed-by: Ross Brattain <ross.b.brattain@intel.com>
    Reviewed-by: Alain Jebara <alain.jebara@intel.com>
    Reviewed-by: Emma Foley <emma.l.foley@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index 07871f9..415fcdf 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit 07871f9503e4abbc0d4fee05f0b87cce782f5c3c
+Subproject commit 415fcdfc0adbcf79dc1ac17e57cc8240a33f597b