Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "Install xz utility on deployment host"
  - Install xz utility on deployment host

    Functest Smoke test requires additional images to be available
    during testing. One of the images is decompressed using xz and we
    need this to be available on deployment host in order to be able
    to have the images available for Functest execution.

    Change-Id: I5647b3bef37fc55e8c5cc9aec5d0b2c3ea628b8a
    Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>

diff --git a/docs/submodules/releng-xci b/docs/submodules/releng-xci
index 0b2e538..a7337ec 160000 (submodule)
--- a/docs/submodules/releng-xci
+++ b/docs/submodules/releng-xci
@@ -1 +1 @@
-Subproject commit 0b2e5383eb16bfaf8846d1c584ce16f702c25acc
+Subproject commit a7337ec6ddc3d60690278e2bd75bd5892c44c05f