wifi: iwlwifi: mvm: check n_ssids before accessing the ssids

In some versions of cfg80211, the ssids poinet might be a valid one even
though n_ssids is 0. Accessing the pointer in this case will cuase an
out-of-bound access. Fix this by checking n_ssids first.

Fixes: c1a75153 ("iwlwifi: mvm: add adaptive dwell support")
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Reviewed-by: Ilan Peer <ilan.peer@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Link: https://msgid.link/20240513132416.6e4d1762bf0d.I5a0e6cc8f02050a766db704d15594c61fe583d45@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>