Fix wrong group names for 22, 32 px in audio.svg

Summary: Before this fix, the system tray audio widget would try to use the 32px icons where 22px icons should be used.

Reviewers: VDG, Plasma, ngraham

Reviewed By: VDG, ngraham

Subscribers: kde-frameworks-devel

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D20825