iommu/mediatek: Update oas for v7s

This patch only updates oas in different SoCs.

If the SoC supports 4GB-mode and current dram size is 4GB, the oas is 33.
otherwise, it's still 32. In the lastest SoC, the oas is 35bits.
Signed-off-by: NYong Wu <yong.wu@mediatek.com>
Reviewed-by: NTomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-16-yong.wu@mediatek.comSigned-off-by: NWill Deacon <will@kernel.org>

drivers/iommu/mtk_iommu.c

@@ -301,10 +301,14 @@ static int mtk_iommu_domain_finalise(struct mtk_iommu_domain *dom)
 			IO_PGTABLE_QUIRK_ARM_MTK_EXT,
 		.pgsize_bitmap = mtk_iommu_ops.pgsize_bitmap,
 		.ias = MTK_IOMMU_HAS_FLAG(data->plat_data, IOVA_34_EN) ? 34 : 32,
-		.oas = 35,
 		.iommu_dev = data->dev,
 	};
 
+	if (MTK_IOMMU_HAS_FLAG(data->plat_data, HAS_4GB_MODE))
+		dom->cfg.oas = data->enable_4GB ? 33 : 32;
+	else
+		dom->cfg.oas = 35;
+
 	dom->iop = alloc_io_pgtable_ops(ARM_V7S, &dom->cfg, data);
 	if (!dom->iop) {
 		dev_err(data->dev, "Failed to alloc io pgtable\n");