This will also be useful for MLO duplicate multicast
detection, but add it already here and use it in one
place that trivially converts.

Link: https://msgid.link/20240129200456.f0ff49c80006.I850d2785ab1640e56e262d3ad7343b87f6962552@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>