Remove part of comment about returning a boolean from ReadData since the
function doesn't return anything (and hasn't for more than 8 years).

R=yangguo

Change-Id: Ie38d68ef36077d08faecc8540c5de050472142ba
Reviewed-on: https://chromium-review.googlesource.com/1174535Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55126}