net: designware: Rename the driver var name to eth_designware

The driver variable name is eth_sandbox, which is probably a copy-paste
mistake. Fix it.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/net/designware.c

@@ -612,7 +612,7 @@ static const struct udevice_id designware_eth_ids[] = {
 	{ }
 };
 
-U_BOOT_DRIVER(eth_sandbox) = {
+U_BOOT_DRIVER(eth_designware) = {
 	.name	= "eth_designware",
 	.id	= UCLASS_ETH,
 	.of_match = designware_eth_ids,