mlxsw: spectrum: Reduce priority of locally delivered packets

To align with recent recommended values. Will be configurable by future
patches.

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