PM/devfreq: Remove redundant put_device()

When unregistering devfreq device (devfreq_remove_device()),
there is an additional call to put_device,
after device_unregister().This causes data aborts in case
of access to a kobj in put_device(), that was already freed
by preceding device_unregister()

CRs-Fixed: 841819
Change-Id: I98bd9e4cc9ecfbc48a0bfe72fc47e362a6697741
Signed-off-by: Hanumant Singh <hanumant@codeaurora.org>