Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "Simplify the serial config"
  - Simplify the serial config

    The current configuration only dumps the booting info into a file and
    the pty does not work (i.e. virsh console opnfv returns a failure
    because it cannot find a character device). After some investigations,
    it is apparently impossible to have both active:

    https://github.com/Mirantis/virtlet/issues/249

    Therefore, we should remove the pty part of the xml. To connect to the
    VM in case of network problems, we can always use vnc.

    Apart from that, the console part is not necessary as libvirt will
    create that one for us

    Change-Id: I80a59163b4ba4e6bff34cb5378893201e93ddb87
    Signed-off-by: Manuel Buil <mbuil@suse.com>

diff --git a/docs/submodules/releng-xci b/docs/submodules/releng-xci
index 6e35b28..3f7060b 160000 (submodule)
--- a/docs/submodules/releng-xci
+++ b/docs/submodules/releng-xci
@@ -1 +1 @@
-Subproject commit 6e35b2821d93d9ac58f354bff81a60581bc882e0
+Subproject commit 3f7060ba0ff61cd70dd8d58640b50c278c1b966e