connman: do not skip cleanup_device 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.

Reference:
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commit 1b87cd7535a360dae57e3238829c91476853af68
Author: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Date:   Mon Oct 7 16:06:10 2013 +0300

    device: Do not cleanup already provisioned interfaces
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Remove our workaround to get connman running in NFS mode, without
bringing down the interface.

Signed-off-by: Srikanth Krishnakar <Srikanth_Krishnakar@mentor.com>