Bluetooth: Remove check for valid LTK authenticated parameter

The LTK authenticated parameter is the key type of the LTK and similar
to link keys there is no need to check the currently supported values.

For possible future improvements, the kernel will only use key types
it knows about and just ignore all the other ones.

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