Update git submodules

* Update docs/submodules/yardstick from branch 'master'
  - Merge "ansible: add grub.cfg hugepages regexp replace"
  - ansible: add grub.cfg hugepages regexp replace

    when building the image in chroot we can't run
    update-grub of grub-mkconfig because both commands
    probe for root partitions, which doesn't work
    in the chroot.

    Instead we manually regexp replace the kernel boot
    line in /boot/**/grub*.cfg

    Change-Id: I31fac2a3db4d1d044f11357b1715119066509676
    Signed-off-by: Ross Brattain <ross.b.brattain@intel.com>

diff --git a/docs/submodules/yardstick b/docs/submodules/yardstick
index e3d1593..570cb78 160000 (submodule)
--- a/docs/submodules/yardstick
+++ b/docs/submodules/yardstick
@@ -1 +1 @@
-Subproject commit e3d159300e64bdd222d8c397bacbc1f26ee3246d
+Subproject commit 570cb78d5906143d19d95bf2d7fe1764e52cf68b