regulator: core: put debugfs consumer handle when unregistering a regulator

Ensure that regulator_put() is called on the core debugfs
consumer pointer for a given regulator when the debugfs interface
is no longer needed.  This includes inside of the
regulator_unregister() function as well as in the error return
path of rdev_init_debugfs().

Change-Id: I10563ae1716f31bdc5840d22633fdbfe278330f1
Signed-off-by: David Collins <collinsd@codeaurora.org>