wifi: iwlwifi: mld: change cluster_id type to u8 array

wifi: iwlwifi: mld: change cluster_id type to u8 array

While the cluster_id is two bytes long, it is just the last two bytes of
the cluster ID MAC address. This does not really map to a big or little
endian data type. Switch it to use an array to avoid confusion and
adjust all users so that they do the right thing independent of
endianness.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Reviewed-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20260111193638.80921dc7d305.I56c2bbe0bfc6ee02782bc5d69fda2ac77f3502c4@changeid