scsi: core: Remove Scsi_Host.shost_dev_attr_groups

Simplify the scsi_host_alloc() implementation by setting the shost_class
.dev_groups member instead of copying all host attribute group pointers
into the shost_dev_attr_groups[] array.

Link: https://lore.kernel.org/r/20211116223115.2103031-1-bvanassche@acm.org
Cc: Steffen Maier <maier@linux.ibm.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Suggested-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>