Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Add the internal_vip(172.29.236.222) to used_ip

    The IP in used_ip will not be used later
    otherwise internal_vip may be assigned to lxc container,
    which will cause issue during deploying

    Change-Id: I9834dfa9b218b4dd23e20c8d57e05bb806dafa7b
    Signed-off-by: wutianwei <wutianwei1@huawei.com>

diff --git a/docs/submodules/releng-xci b/docs/submodules/releng-xci
index 9b0b4e1..639ac5a 160000 (submodule)
--- a/docs/submodules/releng-xci
+++ b/docs/submodules/releng-xci
@@ -1 +1 @@
-Subproject commit 9b0b4e1979633c4320dc0dea0707910c36cb056d
+Subproject commit 639ac5a794f961fb2a8db3cb3fb19681de26ab3c