Use correct easing type values

Summary:
BUG: 382834

Per the QML specification, the animation Easing.InQuad should be specified with easing.type, not easing.

Test Plan:
run kscreenlocker --testing

The console output should not display a warning about the animation.

Reviewers: davidedmundson

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D6970