stmmac: dwmac-loongson: fix uninitialized variable in loongson_dwmac_probe()

The "mdio" variable is never set to false.  Also it should be a bool
type instead of int.

Fixes: 30bba69d ("stmmac: pci: Add dwmac support for Loongson")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c

@@ -49,7 +49,8 @@ static int loongson_dwmac_probe(struct pci_dev *pdev, const struct pci_device_id
 {
 	struct plat_stmmacenet_data *plat;
 	struct stmmac_resources res;
-	int ret, i, mdio;
+	bool mdio = false;
+	int ret, i;
 	struct device_node *np;
 
 	np = dev_of_node(&pdev->dev);