Bluetooth: Provide option to enable/disable debugfs information

The Bluetooth controllers can export extensive information about
internal states via debugfs. This patch provides an option to
choose if these information are provided or not.

For backwards compatibility with existing kernel configuration,
this option defaults to yes.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>