Merge branch 'Fix-IPv6-peer-route-update'

Hangbin Liu says:

====================
Fix IPv6 peer route update

Currently we have two issues for peer route update on IPv6.
1. When update peer route metric, we only updated the local one.
2. If peer address changed, we didn't remove the old one and add new one.

The first two patches fixed these issues and the third patch add new
tests to cover it.

With the fixes and updated test:
]# ./fib_tests.sh
IPv6 prefix route tests
    TEST: Default metric                                                [ OK ]
    TEST: User specified metric on first device                         [ OK ]
    TEST: User specified metric on second device                        [ OK ]
    TEST: Delete of address on first device                             [ OK ]
    TEST: Modify metric of address                                      [ OK ]
    TEST: Prefix route removed on link down                             [ OK ]
    TEST: Prefix route with metric on link up                           [ OK ]
    TEST: Set metric with peer route on local side                      [ OK ]
    TEST: User specified metric on local address                        [ OK ]
    TEST: Set metric with peer route on peer side                       [ OK ]
    TEST: Modify metric with peer route on local side                   [ OK ]
    TEST: Modify metric with peer route on peer side                    [ OK ]

IPv4 prefix route tests
    TEST: Default metric                                                [ OK ]
    TEST: User specified metric on first device                         [ OK ]
    TEST: User specified metric on second device                        [ OK ]
    TEST: Delete of address on first device                             [ OK ]
    TEST: Modify metric of address                                      [ OK ]
    TEST: Prefix route removed on link down                             [ OK ]
    TEST: Prefix route with metric on link up                           [ OK ]
    TEST: Modify metric of .0/24 address                                [ OK ]
    TEST: Set metric of address with peer route                         [ OK ]
    TEST: Modify metric of address with peer route                      [ OK ]

Tests passed:  22
Tests failed:   0
====================

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