wifi: nl80211: fixes to FILS discovery updates

Add a new flag 'update' which is set to true during start_ap()
if (and only if) one of the following two conditions are met:
- Userspace passed an empty nested attribute which indicates that
  the feature should be disabled and templates deleted.
- Userspace passed all the parameters for the nested attribute.

Existing configuration will not be changed while the flag
remains false.

Add similar changes for unsolicited broadcast probe response
transmission.

Signed-off-by: Aloka Dixit <quic_alokad@quicinc.com>
Reviewed-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://lore.kernel.org/r/20230727174100.11721-2-quic_alokad@quicinc.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>