iommu/mediatek: Fix 2 HW sharing pgtable issue

In the commit 4f956c9 ("iommu/mediatek: Move domain_finalise into
attach_device"), I overlooked the sharing pgtable case.
After that commit, the "data" in the mtk_iommu_domain_finalise always is
the data of the current IOMMU HW. Fix this for the sharing pgtable case.

Only affect mt2712 which is the only SoC that share pgtable currently.

Fixes: 4f956c9 ("iommu/mediatek: Move domain_finalise into attach_device")
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/r/20220503071427.2285-5-yong.wu@mediatek.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/mtk_iommu.c

@@ -446,7 +446,7 @@ static void mtk_iommu_domain_free(struct iommu_domain *domain)
 static int mtk_iommu_attach_device(struct iommu_domain *domain,
 				   struct device *dev)
 {
-	struct mtk_iommu_data *data = dev_iommu_priv_get(dev);
+	struct mtk_iommu_data *data = dev_iommu_priv_get(dev), *frstdata;
 	struct mtk_iommu_domain *dom = to_mtk_domain(domain);
 	struct device *m4udev = data->dev;
 	int ret, domid;
@@ -456,7 +456,10 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
 		return domid;
 
 	if (!dom->data) {
-		if (mtk_iommu_domain_finalise(dom, data, domid))
+		/* Data is in the frstdata in sharing pgtable case. */
+		frstdata = mtk_iommu_get_m4u_data();
+
+		if (mtk_iommu_domain_finalise(dom, frstdata, domid))
 			return -ENODEV;
 		dom->data = data;
 	}