wifi: iwlwifi: mld: use spec link id and not FW link id

In missed beacon handling, we compare the FW link id to the
bss_param_ch_cnt_link_id, which is a spec link id. Fix it.

Reviewed-by: Somashekhar Puttagangaiah <somashekhar.puttagangaiah@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250723094230.2104f8cac836.I25ed77c2b87bde82a9153e2aa26e09b8a42f6ee3@changeid