evdev: use a udev_device instead of separate sysname/syspath/devnode

evdev: use a udev_device instead of separate sysname/syspath/devnode

Using a udev_device instead of the various bits separately safes us
re-initializing udev contexts whenever we need to compare the device. And
having the actual udev device makes it a bit easier to ensure that we're not
re-initializing a different device as a current one.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>