Use "futility" to replace commands that are symlink to futility.

Call `futility` directly because it has more features that not available
from the symlink commands, and also to reduce dependency of files.

BUG=None
TEST=make test

Change-Id: I9f6654cf3769bc97f5afb3f26a1f62c95a4af6ff
Reviewed-on: https://chromium-review.googlesource.com/643686
Commit-Ready: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Yong Hong <yhong@google.com>
diff --git a/py/gooftool/commands.py b/py/gooftool/commands.py
index f51abcc..67788c7 100755
--- a/py/gooftool/commands.py
+++ b/py/gooftool/commands.py
@@ -417,7 +417,7 @@
   """Zero out the GBB flags, in preparation for transition to release state.
 
   No GBB flags are set in release/shipping state, but they are useful
-  for factory/development.  See "gbb_utility --flags" for details.
+  for factory/development.  See "futility gbb --flags" for details.
   """
 
   GetGooftool(options).ClearGBBFlags()