Bluetooth: Check for valid key->authenticated value for LTKs

This patch adds necessary checks for the two allowed values of the
authenticated parameter of each Long Term Key, i.e. 0x00 and 0x01. If
any other value is encountered the valid response is to return invalid
params to user space.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>