Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - [baremetal] idf for opnfv_vm and update the pdf

    Physical hardware PODs provide a pdf and a idf to describe hardware and other
    information (e.g. what is the purpose for each interface). To reuse the
    same code for opnfv vm and also become consistent, we should also describe
    the opnfv vm with an idf and a pdf. This patch simplifies what needs to
    be done for baremetal, especially for this (future) patch:

    https://gerrit.opnfv.org/gerrit/#/c/60797/11

    As we add an idf, we should update dynamic_inventory and how we create
    the opnfv vm. Obviously, he opnfv_vm.yml gets removed.

    Change-Id: I930728474631fc214e4a9adc8581e0c16d230176
    Signed-off-by: Manuel Buil <mbuil@suse.com>

diff --git a/docs/submodules/releng-xci b/docs/submodules/releng-xci
index 013bfff..3fe7559 160000 (submodule)
--- a/docs/submodules/releng-xci
+++ b/docs/submodules/releng-xci
@@ -1 +1 @@
-Subproject commit 013bfffe38ab9a6c86a4a6e3bc2d08a5b5aedcbd
+Subproject commit 3fe75598de97c73c95d83739e6ed11277b619988