net: Fix error handling in sb_eth_raw_ofdata_to_platdata()

At present this stores the error number in an unsigned int so an error is
never detected. Use the existing signed variable instead.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/drivers/net/sandbox-raw.c b/drivers/net/sandbox-raw.c
index 09cc678..7e6625d 100644
--- a/drivers/net/sandbox-raw.c
+++ b/drivers/net/sandbox-raw.c
@@ -152,7 +152,6 @@
 	struct eth_pdata *pdata = dev_get_platdata(dev);
 	struct eth_sandbox_raw_priv *priv = dev_get_priv(dev);
 	const char *ifname;
-	u32 local;
 	int ret;
 
 	pdata->iobase = dev_read_addr(dev);
@@ -173,10 +172,10 @@
 		       priv->host_ifindex, priv->host_ifname);
 	}
 
-	local = sandbox_eth_raw_os_is_local(priv->host_ifname);
-	if (local < 0)
-		return local;
-	priv->local = local;
+	ret = sandbox_eth_raw_os_is_local(priv->host_ifname);
+	if (ret < 0)
+		return ret;
+	priv->local = ret;
 
 	return 0;
 }