mlxsw: spectrum_trap: Do not initialize dedicated discard policer

The policer is now initialized as part of the registration with devlink,
so there is no need to initialize it before the registration.

Remove the initialization.

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