tdf#160706 speed up loading conditional formatting rule in XLS (3)

the comment when calling MakeCellStyleSheet does not match the
implementation, so make the implementation match the comment.
i.e. if there is an existing stylesheet with that name, just return it.

Reduces load time for me from 47s to 33s

Change-Id: If1bd08baf8515933b87c075d9eef04bc0a125357
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/166241
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

0 files changed, 0 insertions, 0 deletions