and drop unused FormulaValue enumerator

Change-Id: Ide6026b841db224947d7d559c110dfc7da3cd975
Reviewed-on: https://gerrit.libreoffice.org/34467Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>