sandbox: Remove eth2addr from environment

DSA interfaces use the same mac address for each interface, unless
instructed otherwise. Just set eth4addr and let eth2addr and eth7addr be
set automatically.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/board/sandbox/sandbox.env b/board/sandbox/sandbox.env
index 6dedc75..88ed7a9 100644
--- a/board/sandbox/sandbox.env
+++ b/board/sandbox/sandbox.env
@@ -6,7 +6,6 @@
 stderr=serial,vidconsole
 
 ethaddr=02:00:11:22:33:44
-eth2addr=02:00:11:22:33:48
 eth3addr=02:00:11:22:33:45
 eth4addr=02:00:11:22:33:48
 eth5addr=02:00:11:22:33:46