Make sure the device is valid when setting the tap button map

Fixes #34

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
2 jobs for wip/check-device-settapbuttonmap in 46 seconds (queued for 1 second)
Status Job ID Name Coverage
  Containers
passed fedora@container_build #8686409

00:00:12

 
  Build
passed fedora:33@default-build #8686410

00:00:34