Merge branch 'ipv6-update-route-when-delete-saddr'

Hangbin Liu says:

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ipv6: update route when delete source address

Currently, when remove an address, the IPv6 route will not remove the
prefer source address when the address is bond to other device. Fix this
issue and add related tests as Ido and David suggested.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>