Comment # 67 on bug 1175599 from Stefan Dirsch

Ok. Apparently now "evdev" driver took over keyboard support and "synaptics"
driver touchpad support. Not sure why they are loaded if you removed everything
in /etc/X11/xorg.conf.d. Hmm ... maybe the files for evdev and synaptics are
still there ...

This also means the "libinput" driver would be the culprit here (or at least
*is* together with the updated kernel) and removing xf86-input-libinput package
would be a workaround for you. Unfortunately you now removed content in
/etc/X11/xorg.conf.d and to bring this back you would need to reinstall some
packages, probably these are:

  systemd 
  xf86-input-evdev 
  xorg-x11-server  
  xf86-input-synaptics

Then uninstall

  xf86-input-libinput

Hope this gives you a useful workaround. Why libinput driver no longer works
together with updated kernel I have no idea at the moment.