net: eth: altera: do not free array priv->mdio->irq

priv->mdio->irq used to be allocated and required freeing, but it
is now a fixed sized array and should no longer be free'd.

Issue detected using static analysis with CoverityScan

Fixes: e7f4dc35 ("mdio: Move allocation of interrupts into core")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/altera/altera_tse_main.c

@@ -193,7 +193,6 @@ static void altera_tse_mdio_destroy(struct net_device *dev)
 			    priv->mdio->id);
 
 	mdiobus_unregister(priv->mdio);
-	kfree(priv->mdio->irq);
 	mdiobus_free(priv->mdio);
 	priv->mdio = NULL;
 }