connman: do not skip cleanup_devices function

JIRA: SB-3096

We have better solution in existing connman cleanup_device function
that won't change the interface state and doesn't bring it down.

Upstream commit:

commit 1b87cd7
Author: Jukka Rissanen jukka.rissanen@linux.intel.com
Date: Mon Oct 7 16:06:10 2013 +0300

device: Do not cleanup already provisioned interfaces

Remove our workaround to get connman running in NFS mode, without
bringing down the interface.

Signed-off-by: Srikanth Krishnakar <Srikanth_Krishnakar@mentor.com>