LinuxKPI: 802.11: rework MC/configure_filter

(*prepare_multicast)(), for the drivers we support, is iwlwifi(4)-specific.
If it is not available do not let us stop from calling (*configure_filter)()
at least as well.
In addition to the interface setting mc_all_multi, if we have no way to
prepare the multicast filter list this way, set FIF_ALLMULTI for now.
This seems to help some with rtw89 but does not help me with other drivers
yet to get IPv6 link-local (e.g., ff02::1%wlan0) going.
This should also help in case we are scanning and are setting
FIF_BCN_PRBRESP_PROMISC . We should go and review the full FIF_ list and
start adding conditional support for the other options too.

Sponsored by: The FreeBSD Foundation
PR: 281982
MFC after: 3 days