Fix Ethernet init() return codes

Change return values of init() functions in all Ethernet drivers to conform
to the following:

    >=0: Success
    <0:  Failure

All drivers going forward should return 0 on success.  Current drivers that
return 1 on success were left as-is to minimize changes.

Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
Acked-by: Stefan Roese <sr@denx.de>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Kim Phillips <kim.phillips@freescale.com>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Acked-By: Timur Tabi <timur@freescale.com>
diff --git a/drivers/net/uli526x.c b/drivers/net/uli526x.c
index 1267c57..8460f69 100644
--- a/drivers/net/uli526x.c
+++ b/drivers/net/uli526x.c
@@ -279,12 +279,12 @@
 	db->desc_pool_ptr = (uchar *)&desc_pool_array[0];
 	db->desc_pool_dma_ptr = (dma_addr_t)&desc_pool_array[0];
 	if (db->desc_pool_ptr == NULL)
-		return 0;
+		return -1;
 
 	db->buf_pool_ptr = &buf_pool[0];
 	db->buf_pool_dma_ptr = (dma_addr_t)&buf_pool[0];
 	if (db->buf_pool_ptr == NULL)
-		return 0;
+		return -1;
 
 	db->first_tx_desc = (struct tx_desc *) db->desc_pool_ptr;
 	db->first_tx_desc_dma = db->desc_pool_dma_ptr;
@@ -331,7 +331,7 @@
 	db->cr6_data |= ULI526X_TXTH_256;
 	db->cr0_data = CR0_DEFAULT;
 	uli526x_init(dev);
-	return 1;
+	return 0;
 }
 
 static void uli526x_disable(struct eth_device *dev)