Bluetooth: Add option for disabling legacy ioctl interfaces

The legacy ioctl interfaces are only useful for BR/EDR operation and
since Linux 3.4 no longer needed anyway. This options allows disabling
them alltogether and use only management interfaces for setup and
control.

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