srp_daemon: Recognize more configuration options

Make the code for parsing the id_ext, ioc_guid, dgid, service_id and
pkey options more systematic and easier to extend. Add support for
parsing the options comp_vector, queue_size and use_fast_reg.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
srp_daemon: Really unsubscribe before exiting

Signed-off-by: Bart Van Assche <bvanassche@acm.org>