s390/mm: Fix clearing storage keys for huge pages

The function __storage_key_init_range() expects the end address to be
the first byte outside the range to be initialized. I.e. end - start
should be the size of the area to be initialized.

The current code works because __storage_key_init_range() will still loop
over every page in the range, but it is slower than using sske_frame().

Fixes: 3afdfca ("s390/mm: Clear skeys for newly mapped huge guest pmds")
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20240416114220.28489-3-imbrenda@linux.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

Author: Claudio Imbrenda

arch/s390/mm/hugetlbpage.c

@@ -139,7 +139,7 @@ static void clear_huge_pte_skeys(struct mm_struct *mm, unsigned long rste)
 	}
 
 	if (!test_and_set_bit(PG_arch_1, &page->flags))
-		__storage_key_init_range(paddr, paddr + size - 1);
+		__storage_key_init_range(paddr, paddr + size);
 }
 
 void __set_huge_pte_at(struct mm_struct *mm, unsigned long addr,