mlxsw: Add new FIB entry type for reject routes

Currently, packets that cannot be routed in hardware (e.g., nexthop
device is not upper of mlxsw), are trapped to the kernel for forwarding.
Such packets are trapped using "RTR_INGRESS0" trap. This trap also traps
packets that hit reject routes (e.g., "unreachable") so that the kernel
will generate the appropriate ICMP error message for them.

Subsequent patch will need to only report to devlink packets that hit a
reject route, which is impossible as long as "RTR_INGRESS0" is
overloaded like that.

Solve this by using "RTR_INGRESS1" trap for packets that hit reject
routes.

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