scsi: sg: drop nth_page() usage within SG entry

scsi: sg: drop nth_page() usage within SG entry

It's no longer required to use nth_page() when iterating pages within a
single SG entry, so let's drop the nth_page() usage.

Link: https://lkml.kernel.org/r/20250901150359.867252-32-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Doug Gilbert <dgilbert@interlog.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>