Bluetooth: fix debugfs registration

Bluetooth: fix debugfs registration

Since commit ec6cef9cd98d ("Bluetooth: Fix SMP channel registration for
unconfigured controllers") the debugfs interface for unconfigured
controllers will be created when the controller is configured.

There is however currently nothing preventing a controller from being
configured multiple time (e.g. setting the device address using btmgmt)
which results in failed attempts to register the already registered
debugfs entries:

	debugfs: File 'features' in directory 'hci0' already present!
	debugfs: File 'manufacturer' in directory 'hci0' already present!
	debugfs: File 'hci_version' in directory 'hci0' already present!
	...
	debugfs: File 'quirk_simultaneous_discovery' in directory 'hci0' already present!

Add a controller flag to avoid trying to register the debugfs interface
more than once.

Fixes: ec6cef9cd98d ("Bluetooth: Fix SMP channel registration for unconfigured controllers")
Cc: stable@vger.kernel.org      # 4.0
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>