mlxsw: spectrum: Align the matchall default case returned value

Align the default case for matchall offload with what's there
for flower.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Acked-by: Yotam Gigi <yotamg@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>