gimp_device_info_set_device(): don't just bail out if a device with
the same name is added again, instead, simply continue and overwrite
the info's old device with the new one.

NOTE that this only happens if something is wrong on the USB or udev
or libinput or whatever side and the same device is present multiple
times. The only "safe" thing is to assume that devices listed earlier
are dead and dangling entities and that the last registered device is
the one actually delivering events.