Update git submodules

* Update docs/submodules/sdnc/oam.git from branch 'master'
  to 15c6cfe1990346af373968693fd7c568003bea11
  - Merge "Fix sdwan-vf-vpn-delete DG by passing vf-module-id"
  - Fix sdwan-vf-vpn-delete DG by passing vf-module-id

    Vf-module-id is passed as it is not passed and
    returned Missing key is getVfModuleId.

    Change-Id: I576f6fd11b97aa1af423837bcd741abc653a2803
    Issue-ID: SDNC-659
    Signed-off-by: Prakash.E <prakash.e@huawei.com>

diff --git a/docs/submodules/sdnc/oam.git b/docs/submodules/sdnc/oam.git
index da9baca..15c6cfe 160000 (submodule)
--- a/docs/submodules/sdnc/oam.git
+++ b/docs/submodules/sdnc/oam.git
@@ -1 +1 @@
-Subproject commit da9bacaddbf914220d80ef412fb8ec4aa7a724e7
+Subproject commit 15c6cfe1990346af373968693fd7c568003bea11