mlxsw: spectrum_flow: Convert a goto to a return

No clean-up is performed at the target label of this goto. Convert it to a
direct return.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>