net/eth: fix a bug in on_ethaddr()

The loop should check all ethenet devices, not only the first device,
to set each specified ethaddr, or it'll cause failure when we use other
devices.

Signed-off-by: Gong Qianyu <Qianyu.Gong@freescale.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/net/eth.c b/net/eth.c
index 2e24b55..e9b22d8 100644
--- a/net/eth.c
+++ b/net/eth.c
@@ -691,6 +691,7 @@
 				memset(dev->enetaddr, 0, 6);
 			}
 		}
+		dev = dev->next;
 	} while (dev != eth_devices);
 
 	return 0;