mlxsw: spectrum_router: Correctly reallocate adjacency entries

[ Upstream commit a59b7e0246774e28193126fe7fdbbd0ae9c67dcc ]

mlxsw_sp_nexthop_group_mac_update() is called in one of two cases:

1) When the MAC of a nexthop needs to be updated
2) When the size of a nexthop group has changed

In the second case the adjacency entries for the nexthop group need to
be reallocated from the adjacency table. In this case we must write to
the entries the MAC addresses of all the nexthops that should be
offloaded and not only those whose MAC changed. Otherwise, these entries
would be filled with garbage data, resulting in packet loss.

Fixes: a7ff87ac ("mlxsw: spectrum_router: Implement next-hop routing")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>