[Touchpad KCM] Do not crash in case there is no touchpad
Summary:
BUG: 408325
FIXED-IN: 5.16.2
Reviewers: ngraham, romangg, atulbi, Plasma, davidedmundson
Reviewed By: ngraham, romangg, Plasma, davidedmundson
Subscribers: davidedmundson, plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D21884