s390/mm: always use PAGE_KERNEL when mapping pages

Always use PAGE_KERNEL when re-enabling pages within the kernel
mapping due to debug pagealloc. Without using this pgprot value
pte_mkwrite() and pte_wrprotect() won't work on such mappings after an
unmap -> map cycle anymore.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/mm/pageattr.c

@@ -138,7 +138,7 @@ void __kernel_map_pages(struct page *page, int numpages, int enable)
 		nr = min(numpages - i, nr);
 		if (enable) {
 			for (j = 0; j < nr; j++) {
-				pte_val(*pte) = __pa(address);
+				pte_val(*pte) = address | pgprot_val(PAGE_KERNEL);
 				address += PAGE_SIZE;
 				pte++;
 			}