mlxsw: spectrum: Use same trap group for local routes and link-local destination

Packets with an IPv6 link-local destination (i.e., fe80::/10) should not
be forwarded and are therefore trapped to the CPU for local delivery.
Since these packets are trapped for the same logical reason as packets
hitting local routes, associate both traps with the same group.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>