Bluetooth: Add management events for controller addition & removal

This patch adds Bluetooth Management interface events for controller
addition and removal. The events correspond to the existing HCI_DEV_REG
and HCI_DEV_UNREG stack internal events.

Signed-off-by: Johan Hedberg <johan.hedberg@nokia.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>