Bluetooth: Make auth_req mask dependent on SC enabled or not

If we haven't enabled SC support on our side we should use the same mask
for the authentication requirement as we were using before SC support
was added, otherwise we should use the extended mask for SC.

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