Update git submodules

* Update docs/submodules/apex from branch 'master'
  - Merge "Update VPP/ODL versions for FDIO scenarios"
  - Update VPP/ODL versions for FDIO scenarios

    Pin the same set of FDIO and OpenDaylight versions for all fdio
    scenarios.

    Note that fdio_netvirt-fdio still uses a customized ODL version.

    os-net-config-pr: 7
    JIRA: APEX-451

    Change-Id: Ic5ac5aeead9967fe383447e23653276cde2dfe60
    Signed-off-by: Feng Pan <fpan@redhat.com>

diff --git a/docs/submodules/apex b/docs/submodules/apex
index d81cd20..e74b8e1 160000 (submodule)
--- a/docs/submodules/apex
+++ b/docs/submodules/apex
@@ -1 +1 @@
-Subproject commit d81cd2087be5edf5d2c0d98ad71a63360ae8511f
+Subproject commit e74b8e1e863e9d0e541a897e5681275cad40db8a