Update git submodules

* Update docs/submodules/sdnc/oam.git from branch 'master'
  to 7573a1d8192032c8a7af0e8e61f359e5b22b2fc4
  - Merge "Add a DG for PNF software rollback action"
  - Add a DG for PNF software rollback action

    Add a DG for LCM:rollback action to support PNF software rollback.

    Change-Id: Id82e1dc20a0792713fb079ea302f7d71e2949fc8
    Issue-ID: SDNC-670
    Signed-off-by: Enbo Wang <wangenbo@huawei.com>

diff --git a/docs/submodules/sdnc/oam.git b/docs/submodules/sdnc/oam.git
index 30a7591..7573a1d 160000 (submodule)
--- a/docs/submodules/sdnc/oam.git
+++ b/docs/submodules/sdnc/oam.git
@@ -1 +1 @@
-Subproject commit 30a75914225f313fac7a40b6bc2a2d0d782fc112
+Subproject commit 7573a1d8192032c8a7af0e8e61f359e5b22b2fc4