mlxsw: spectrum: fix swapped order of arguments packets and bytes

The arguments packets and bytes to call mlxsw_sp_acl_rule_get_stats are
in the wrong order. Fix this by swapping them.

Detected by CoverityScan, CID#1419705 ("Arguments in wrong order")

Fixes: 7c1b8eb1

 ("mlxsw: spectrum: Add support for TC flower offload statistics")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>