boards: get mac address from environment

The boards that get converted here to use the environment for the mac
address rather than global data:
	debris
	mgcoge
	mgsuvd
	muas3001
	netstal
	pn62
	sixnet
	vcma9
	xilinx (the ones that use xilinx_enet)

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
CC: Ben Warren <biggerbadderben@gmail.com>
CC: Sangmoon Kim <dogoil@etinsys.com>
CC: Heiko Schocher <hs@denx.de>
CC: David Mueller <d.mueller@elsoft.ch>
CC: Niklaus Giger <niklaus.giger@netstal.com>
CC: Wolfgang Grandegger <wg@denx.de>
CC: Dave Ellis <DGE@sixnetio.com>
CC: Ricardo Ribalda <ricardo.ribalda@uam.es>
diff --git a/board/etin/debris/debris.c b/board/etin/debris/debris.c
index 227c49a..a971af3 100644
--- a/board/etin/debris/debris.c
+++ b/board/etin/debris/debris.c
@@ -173,9 +173,13 @@
 
 int misc_init_r(void)
 {
-	/* Write ethernet addr in NVRAM for VxWorks */
-	nvram_write(CONFIG_ENV_ADDR + CONFIG_SYS_NVRAM_VXWORKS_OFFS,
-			(char*)&gd->bd->bi_enetaddr[0], 6);
+	uchar ethaddr[6];
+
+	if (eth_getenv_enetaddr("ethaddr", ethaddr))
+		/* Write ethernet addr in NVRAM for VxWorks */
+		nvram_write(CONFIG_ENV_ADDR + CONFIG_SYS_NVRAM_VXWORKS_OFFS,
+				ethaddr, 6);
+
 	return 0;
 }