Merge branch 'bonding-fix-ns-targets-not-work-on-hardware-nic'

Hangbin Liu says:

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bonding: fix ns targets not work on hardware NIC

The first patch fixed ns targets not work on hardware NIC when bonding
set arp_validate.

The second patch add a related selftest for bonding.

v4: Thanks Nikolay for the comments:
    use bond_slave_ns_maddrs_{add/del} with clear name
    fix comments typos
    remove _slave_set_ns_maddrs underscore directly
    update bond_option_arp_validate_set() change logic
v3: use ndisc_mc_map to convert the mcast mac address (Jay Vosburgh)
v2: only add/del mcast group on backup slaves when arp_validate is set (Jay Vosburgh)
    arp_validate doesn't support 3ad, tlb, alb. So let's only do it on ab mode.
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Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>