[SCSI] struct device - replace bus_id with dev_name(), dev_set_name()

[jejb: limit ioctl to returning 20 characters to avoid overrun
       on long device names and add a few more conversions]
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>