D22521: Fix a mistake with "Pb"

[Yi-Jyun Pan]

ppeter added a reviewer: Frameworks.

REPOSITORY
  R292 KUnitConversion

REVISION DETAIL
  https://phabricator.kde.org/D22521

To: ppeter, #frameworks
Cc: kde-frameworks-devel, LeGast00n, sbergeron, michaelh, ngraham, bruns