Bluetooth: Update New CSRK event to match latest specification

The 'master' parameter of the New CSRK event was recently renamed to
'type', with the old values kept for backwards compatibility as
unauthenticated local/remote keys. This patch updates the code to take
into account the two new (authenticated) values and ensures they get
used based on the security level of the connection that the respective
keys get distributed over.

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