emac_irq is declared as:

static irqreturn_t emac_irq(int irq, void *dev_id)
{
       struct net_device *ndev = (struct net_device *)dev_id;
       struct emac_priv *priv = netdev_priv(ndev);
    ... 

	Clearly emac_irq() needs "struct net_device *" as "void *dev_id", so correct this.
Signed-off-by: Tonyliu <Bo.Liu@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>