scsi_sysfs: Fix typo in is_bin_visible()

The test for the existence vpd_pg83 is inverted.

Fixes: 7e47976b ("scsi_sysfs: add 'is_bin_visible' callback")
Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reported-by: Ewan Milne <emilne@redhat.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>