scsi: qla2xxx: Switch to attribute groups

struct device supports attribute groups directly but does not support
struct device_attribute directly. Hence switch to attribute groups.
Additionally, remove qla_insert_tgt_attrs() and replace it with
qla_host_attr_is_visible().

Link: https://lore.kernel.org/r/20211012233558.4066756-41-bvanassche@acm.org


Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>