Remove deprecation warning from create_nmf.py

It's still used all over the place, so the compilation logs are spilled
with warnings

BUG=none
TBR=sbc@chromium.org,binji@chromium.org

Review URL: https://codereview.chromium.org/190283003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255914 0039d316-1c4b-4281-b951-d872f2087c98

native_client_sdk/src/tools/create_nmf.py

@@ -582,7 +582,6 @@ def main(argv):
     remap[parts[0]] = parts[1]
 
   if options.path_prefix:
-    sys.stderr.write('warning: option -P/--path-prefix is deprecated.\n')
     options.lib_prefix = options.path_prefix
 
   for libpath in options.lib_path: