Update git submodules

Update git submodules

* Update docs/submodules/releng from branch 'master'
  - xci: Disable Centos jobs until Intel lab is back

    Due to Intel lab maintenance, the number of slaves will go down so we need
    to have fewer jobs running. Centos is known to be problematic upstream and
    it is better to disable them until the lab is back online to ensure the jobs
    for other distros are impacted less.

    Change-Id: Ifd8624e45282d68bd7acdf283ef7a499e81990e9
    Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>