powerpc/powernv/ioda2: Add 256M IOMMU page size to the default POWER8 case

The sketchy bypass uses 256M pages so add this page size as well.

This should cause no behavioral change but will be used later.

Fixes: 477afd6ea6 "powerpc/ioda: Use ibm,supported-tce-sizes for IOMMU page size mask"
Signed-off-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/powernv/pci-ioda.c

@@ -2925,7 +2925,7 @@ static unsigned long pnv_ioda_parse_tce_sizes(struct pnv_phb *phb)
 		/* Add 16M for POWER8 by default */
 		if (cpu_has_feature(CPU_FTR_ARCH_207S) &&
 				!cpu_has_feature(CPU_FTR_ARCH_300))
-			mask |= SZ_16M;
+			mask |= SZ_16M | SZ_256M;
 		return mask;
 	}