hostapd: rename hostapd multicast_to_unicast option to multicast_to_unicast_all

hostapd: rename hostapd multicast_to_unicast option to multicast_to_unicast_all

There are two feature currently altered by the multicast_to_unicast option.
1. bridge level multicast_to_unicast via IGMP snooping
2. hostapd/mac80211 config multicast_to_unicast setting

The hostapd/mac80211 setting has the side effect of converting *all* multicast
or broadcast traffic into per-station duplicated unicast traffic, which can
in some cases break expectations of various protocols.
It also has been observed to cause ARP lookup failure between stations
connected to the same interface.

The bridge level feature is much more useful, since it only covers actual
multicast traffic managed by IGMP, and it implicitly defaults to 1 already.

Renaming the hostapd/mac80211 option to multicast_to_unicast_all should avoid
unintentionally enabling this feature

Signed-off-by: Felix Fietkau <nbd@nbd.name>