bluetooth: audio: csip: Unlock Non-bonded devices immediately.

Qualification test CSIS/SR/SP/BV-03-C [Lock Timeout]

Specification: Coordinated Set Identification Service Revision v1.0.1
Section 5.3.1.1.

When the server and the client are not bonded and they disconnect when
the value of the Set Member Lock characteristic is set to Locked, the
server shall set the value of the Set Member Lock characteristic to
Unlocked immediately after the disconnection.

Signed-off-by: Henrik Eriksen <heri@demant.com>