fdt: rework fdt_fixup_ethernet() to use env instead of bd_t

Move to using the environment variables 'ethaddr', 'eth1addr', etc..
instead of bd->bi_enetaddr, bi_enet1addr, etc.

This makes the code a bit more flexible to the number of ethernet
interfaces.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/cpu/ppc4xx/fdt.c b/cpu/ppc4xx/fdt.c
index 0323dc5..a97484f 100644
--- a/cpu/ppc4xx/fdt.c
+++ b/cpu/ppc4xx/fdt.c
@@ -130,7 +130,7 @@
 	 * Fixup all ethernet nodes
 	 * Note: aliases in the dts are required for this
 	 */
-	fdt_fixup_ethernet(blob, bd);
+	fdt_fixup_ethernet(blob);
 
 	/*
 	 * Fixup all available PCIe nodes by setting the device_type property