fdt: Deprecate "usbethaddr" usage in fdt_fixup_ethernet()

In fdt_fixup_ethernet() only "usbethaddr" is handled to fix up the
first usb ethernet port MAC address. Other additional usb ethernet
ports are ignored as there is no logic to handle "usbeth%daddr".

It is suggested we should use "ethaddr" for all ethernet devices.
Hence deprecate "usbethaddr" usage in fdt_fixup_ethernet().

This actually reverts commit b1f49ab8c7bad60426b30c134ae065ef77d2dfc1
"ARM: fdt support: Add usbethaddr as an acceptable MAC".

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
On OMAP4 Panda (+ v4.3 kernel)
Tested-by: Tom Rini <trini@konsulko.com>

common/fdt_support.c

@@ -491,18 +491,8 @@ void fdt_fixup_ethernet(void *fdt)
 	if (node < 0)
 		return;
 
-	if (!getenv("ethaddr")) {
-		if (getenv("usbethaddr")) {
-			strcpy(mac, "usbethaddr");
-		} else {
-			debug("No ethernet MAC Address defined\n");
-			return;
-		}
-	} else {
-		strcpy(mac, "ethaddr");
-	}
-
 	i = 0;
+	strcpy(mac, "ethaddr");
 	while ((tmp = getenv(mac)) != NULL) {
 		sprintf(enet, "ethernet%d", i);
 		path = fdt_getprop(fdt, node, enet, NULL);