scsi: target: core: Stop using bdevname()

Just use the %pg format specifier instead.

Link: https://lore.kernel.org/r/20211018065052.1822500-1-hch@lst.de


Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>