powerpc/mm: Use a helper for finding pte bits mapping I/O area

Use a helper instead of open coding with constants. A later patch will
drop the WIMG bits and use PowerISA 3.0 defines.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/ps3/spu.c

@@ -216,7 +216,7 @@ static int __init setup_areas(struct spu *spu)
 	}
 
 	spu->local_store = (__force void *)ioremap_prot(spu->local_store_phys,
-		LS_SIZE, _PAGE_NO_CACHE);
+		LS_SIZE, pgprot_val(pgprot_noncached_wc(__pgprot(0))));
 
 	if (!spu->local_store) {
 		pr_debug("%s:%d: ioremap local_store failed\n",