cgpt: add back format field

Previous commit here accidentally deleted the format field.

BUG=chromium:329112,chromium:339298
TEST=building for sonic doesn't warn anymore

Change-Id: If9fded31ac938d1ee1b9fcb8cd5457ff0bec82b4
Reviewed-on: https://chromium-review.googlesource.com/184302
Reviewed-by: Gaurav Shah <gauravsh@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
1 file changed