drm/arm/malidp: Stop using iommu_present()

iommu_get_domain_for_dev() is already perfectly happy to return NULL
if the given device has no IOMMU. Drop the unnecessary check.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/5049994e6c2ba92c2f30d51850c8929136d0f8ca.1649167878.git.robin.murphy@arm.com

drivers/gpu/drm/arm/malidp_planes.c

@@ -310,17 +310,13 @@ static int malidp_se_check_scaling(struct malidp_plane *mp,
 
 static u32 malidp_get_pgsize_bitmap(struct malidp_plane *mp)
 {
-	u32 pgsize_bitmap = 0;
+	struct iommu_domain *mmu_dom;
 
-	if (iommu_present(&platform_bus_type)) {
-		struct iommu_domain *mmu_dom =
-			iommu_get_domain_for_dev(mp->base.dev->dev);
+	mmu_dom = iommu_get_domain_for_dev(mp->base.dev->dev);
+	if (mmu_dom)
+		return mmu_dom->pgsize_bitmap;
 
-		if (mmu_dom)
-			pgsize_bitmap = mmu_dom->pgsize_bitmap;
-	}
-
-	return pgsize_bitmap;
+	return 0;
 }
 
 /*