x11-drivers/xf86-input-libinput: Update to 0.28.2

Update x11-drivers/xf86-input-libinput to 0.28.2.
This is a bugfix release.
Changelog:
https://lists.x.org/archives/xorg-announce/2019-February/002938.html

PR: 235502
Submitted by: pete@nomadlogic.org
Sponsored by: B3 Init (zeising)