Bluetooth: Discovery parameters per hci_dev

This patch adds discovery parameters to struct hci_dev. This way, we
will be able to configure the discovery parameters per hci device.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Export discovery parameters on debugfs

This patch exports discovery parameters thought debugfs filesystem.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
WIP: Bluetooth: Write discovery parameters

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>