mlxsw: spectrum: qdiscs: Make function mlxsw_sp_qdisc_prio_unoffload static

Fixes the following sparse warning:

drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c:464:1: warning:
 symbol 'mlxsw_sp_qdisc_prio_unoffload' was not declared. Should it be static?
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c

@@ -460,7 +460,7 @@ mlxsw_sp_qdisc_prio_replace(struct mlxsw_sp_port *mlxsw_sp_port,
 	return 0;
 }
 
-void
+static void
 mlxsw_sp_qdisc_prio_unoffload(struct mlxsw_sp_port *mlxsw_sp_port,
 			      struct mlxsw_sp_qdisc *mlxsw_sp_qdisc,
 			      void *params)