[REVIEW-3-6] fix for fdo#53010, use correct length for string

[Markus Mohrhard]

Hey,

[1] fixes the problem with the "is between" conditional format. The
problem was that I missed one character when I calculated the string
length which prevented the import of the values/formulas.

Regards,
Markus

[1] http://cgit.freedesktop.org/libreoffice/core/commit/?id=507305afa0d826b7e3cb3cc9a4b389f0ba854638