scsi: ibmvscsi: Switch to attribute groups

struct device supports attribute groups directly but does not support
struct device_attribute directly. Hence switch to attribute groups.

Link: https://lore.kernel.org/r/20211012233558.4066756-24-bvanassche@acm.org


Acked-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>