Update git submodules
* Update docs/submodules/fuel from branch 'master'
- Merge "states: maas: Stop using maas-stable PPA"
- states: maas: Stop using maas-stable PPA
Currently, Xenial repos provide MaaS 2.2.x, while the PPA bumped it
to 2.3.x. Since we switched to 2.3, we observed a rare wrongful state
transition from 'Deploying' back to 'Ready'.
Drop the PPA, falling back to 2.2 from mainline distro repos.
JIRA: FUEL-312
Change-Id: I3daa118059f37cbeca076da685661c28f3a28a97
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>