typo: VarP (Sample) -> VarP (Population)

Change-Id: Iaa80388952ac38a088874629688d9cf8a5fd456d
(cherry picked from commit 6c0e47e37834d138daf4fecd154881ef5740c9fb)
Signed-off-by: Andras Timar <andras.timar@collabora.com>