mlxsw: spectrum_router: Clear offload indication from IPv6 nexthops on abort

mlxsw: spectrum_router: Clear offload indication from IPv6 nexthops on abort

Unlike IPv4, in IPv6 there is no unique structure to represent the
nexthop and both the route and nexthop information are squashed to the
same structure ('struct fib6_info'). In order to improve resource
utilization the driver consolidates identical nexthop groups to the same
internal representation of a nexthop group.

Therefore, when the offload indication of a nexthop changes, the driver
needs to iterate over all the linked fib6_info and toggle their offload
flag accordingly.

During abort, all the routes are removed from the device and unlinked
from their nexthop group. The offload indication is cleared just before
the group is destroyed, but by that time no fib6_info is linked to the
group and the offload indication remains set.

Fix this by clearing the offload indication just before dropping the
reference from the nexthop.

Fixes: 9ef5e5c8aae8 ("mlxsw: spectrum_router: Set hardware flags for routes")
Reported-by: Alex Kushnarov <alexanderk@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Tested-by: Alex Kushnarov <alexanderk@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>