s390/cmm: add missing virt_to_phys() conversion

diag10_range() expects a pfn, however the current cmm code is shifting
a virtual address, instead of a physical address by PAGE_SHIFT bits,
which would give a wrong result in case if V!=R.

Use virt_to_pfn() to fix this.

Note: this currently doesn't fix a real bug, since virtual addresses
are indentical to physical ones.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/mm/cmm.c

@@ -90,7 +90,7 @@ static long cmm_alloc_pages(long nr, long *counter,
 			} else
 				free_page((unsigned long) npa);
 		}
-		diag10_range(addr >> PAGE_SHIFT, 1);
+		diag10_range(virt_to_pfn(addr), 1);
 		pa->pages[pa->index++] = addr;
 		(*counter)++;
 		spin_unlock(&cmm_lock);