s390: struct device - replace bus_id with dev_name(), dev_set_name()

Cc: schwidefsky@de.ibm.com
Cc: linux-s390@vger.kernel.org
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>