Fix SkSemaphore comments.

Change-Id: I14fc03fcb73bad61daed7c4cd3ed12bfae6b1217
Reviewed-on: https://skia-review.googlesource.com/8880
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
1 file changed