ipv6: prevent router_solicitations for team port

The issue fixed for bonding in commit c2edacf8 ("bonding / ipv6: no
addrconf for slaves separately from master") also exists in team driver.
However, we can't just disable ipv6 addrconf for team ports, as 'teamd'
will need it when nsns_ping watch is used in the user space.

Instead of preventing ipv6 addrconf, this patch only prevents RS packets
for team ports, as it did in commit b52e1cce

 ("ipv6: Don't send rs
packets to the interface of ARPHRD_TUNNEL").

Note that we do not prevent DAD packets, to avoid the changes getting
intricate / hacky. Also, usually sysctl dad_transmits is set to 1 and
only 1 DAD packet will be sent, and by now no libteam user complains
about DAD packets on team ports, unlike RS packets.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>