Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "APEX: iso verify fixes"
  - APEX: iso verify fixes

    The current implementation of iso verify can potentially block indefinitely
    and/or return incorrect string matching results. This patch changes iso verify
    to use log file instead of tcp serial console.

    Change-Id: I89accc9c2165836a23a21a223fa33e920c529772
    Signed-off-by: Feng Pan <fpan@redhat.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 2c02c55..6a80a19 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 2c02c556fdf29e41f04ad16277efb0c82206cec7
+Subproject commit 6a80a19f991a9ba91190187554fec105e9c79ae1