cxgb4: make function 'cxgb4_mqprio_free_hw_resources' static

Fix sparse warnings:

drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_mqprio.c:242:6: warning: symbol 'cxgb4_mqprio_free_hw_resources' was not declared. Should it be static?
Reported-by: NHulk Robot <hulkci@huawei.com>
Fixes: 2d0cb84d ("cxgb4: add ETHOFLD hardware queue support")
Signed-off-by: Nzhengbin <zhengbin13@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_mqprio.c

@@ -239,7 +239,7 @@ static int cxgb4_mqprio_alloc_hw_resources(struct net_device *dev)
 	return ret;
 }
 
-void cxgb4_mqprio_free_hw_resources(struct net_device *dev)
+static void cxgb4_mqprio_free_hw_resources(struct net_device *dev)
 {
 	struct port_info *pi = netdev2pinfo(dev);
 	struct adapter *adap = netdev2adap(dev);