bnc#881025: Mark axis a percent axis only when all data series are percent.

(cherry picked from commit b8c444a46b2f41dae673c6118d84276be0e6c87d)

Conflicts:
	oox/inc/drawingml/chart/axisconverter.hxx

Change-Id: I302cc1e5b164b2ce9999087293b034ec930951af
Reviewed-on: https://gerrit.libreoffice.org/10124
Reviewed-by: Matúš Kukan <matus.kukan@collabora.com>
Tested-by: Matúš Kukan <matus.kukan@collabora.com>