bcm63xx_enet: delete a redundant assignment

In the function bcm_enetsw_probe(), 'ret' will be assigned by
bcm_enet_change_mtu(), so 'ret = 0' make no sense.

Signed-off-by: Zhang Shengju <[e-mail]>
Signed-off-by: Tang Bin <[e-mail]>
Acked-by: Florian Fainelli <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/broadcom/bcm63xx_enet.c

···
 	if (!res_mem || irq_rx < 0)
 		return -ENODEV;
 
-	ret = 0;
 	dev = alloc_etherdev(sizeof(*priv));
 	if (!dev)
 		return -ENOMEM;