HID: sony: Don't use fw_version/hw_version for sysfs cleanup.

The DS4 dongle reports fw_version and hw_version as 0 when no actual
DS4 is connected to it. This prevents cleaning up sysfs nodes upon
device remove.

This patch decouples sysfs cleanup from the fw_version and hw_version
values by introducing boolean values.

Signed-off-by: Roderick Colenbrander <roderick.colenbrander@sony.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>