Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Modify common patches schema to per branch

    The common patch design doesn't really work across branches very well.
    This patch makes it so the common patches are specified in the same
    file, but on a per branch basis. Making it easier to manage common
    patches per branch.

    Also, includes a fix and adds test coverage to the prep_image method
    where we were referencing 'undercloud_admin_ip' before assignment in a
    case where we were not using ODL and had patches to overcloud.

    Change-Id: I7672947afd826fdc0042361a0139e22d6d5dd864
    Signed-off-by: Tim Rozet <trozet@redhat.com>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index ae5fcc0..c0a4aa9 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit ae5fcc0dd1d19c750cba8d9bf16545f5a7802287
+Subproject commit c0a4aa96bbe70eefb179d59a1267b8115651bba5