net: cosmetic: Name ethaddr variables consistently

Use "_ethaddr" at the end of variables and drop CamelCase.
Make constant values actually 'const'.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/board/ifm/ac14xx/ac14xx.c b/board/ifm/ac14xx/ac14xx.c
index 5d2ab2f..72932ca 100644
--- a/board/ifm/ac14xx/ac14xx.c
+++ b/board/ifm/ac14xx/ac14xx.c
@@ -225,7 +225,7 @@
 		break;
 	}
 
-	if (mac && is_valid_ether_addr(mac)) {
+	if (mac && is_valid_ethaddr(mac)) {
 		eth_setenv_enetaddr("ethaddr", mac);
 		if (mac_diag) {
 			mac_txt = getenv("ethaddr");