google: Include env.h to permit reading the environment

This file reads from the environment but does not include the correct
header. Update it.

Signed-off-by: Simon Glass <sjg@chromium.org>

board/google/chameleonv3/board.c

@@ -2,6 +2,8 @@
 /*
  * Copyright 2022 Google LLC
  */
+
+#include <env.h>
 #include <net.h>
 #include <errno.h>
 #include "mercury_aa1.h"