scsi: core: Remove two host template members that are no longer used

scsi: core: Remove two host template members that are no longer used

All SCSI drivers have been converted to use shost_groups and sdev_groups
instead of shost_attrs or sdev_attrs. Hence remove shost_attrs and
sdev_attrs. Additionally, remove the 'lld_attr_group' members and also
the scsi_convert_dev_attrs() function.

Link: https://lore.kernel.org/r/20211012233558.4066756-47-bvanassche@acm.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>