net: sh_eth: tidyup compile warning

This patch tidyup below warning

${LINUX}/drivers/net/sh_eth.c:1773: warning:
'mdp' may be used uninitialized in this function

Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Kuninori Morimoto <morimoto.kuninori@renesas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/sh_eth.c

@@ -1770,7 +1770,7 @@ static int sh_eth_drv_probe(struct platform_device *pdev)
 	int ret, devno = 0;
 	struct resource *res;
 	struct net_device *ndev = NULL;
-	struct sh_eth_private *mdp;
+	struct sh_eth_private *mdp = NULL;
 	struct sh_eth_plat_data *pd;
 
 	/* get base addr */
@@ -1888,7 +1888,7 @@ out_unregister:
 
 out_release:
 	/* net_dev free */
-	if (mdp->tsu_addr)
+	if (mdp && mdp->tsu_addr)
 		iounmap(mdp->tsu_addr);
 	if (ndev)
 		free_netdev(ndev);