This commit backports fixes from OpenWRT trunk regarding the
multicast-to-unicast feature for the Linux bridge:
* Revert "kernel: disable multicast-to-unicast translation for ipv6 neighbor solicitation (#17625)"
* kernel: bridge, multicast-to-unicast: assign src after pskb_may_pull()
* kernel: bridge, multicast-to-unicast: fix echoes on STA
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
