drm/exynos: remove unnecessary checking to support iommu

Already drm_iommu_attach_device and drm_iommu_detach_device check
whether support iommu internally, so we don't have to call
is_drm_iommu_supported before call them.

Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
diff --git a/drivers/gpu/drm/exynos/exynos7_drm_decon.c b/drivers/gpu/drm/exynos/exynos7_drm_decon.c
index 362532a..2c29635 100644
--- a/drivers/gpu/drm/exynos/exynos7_drm_decon.c
+++ b/drivers/gpu/drm/exynos/exynos7_drm_decon.c
@@ -136,8 +136,7 @@
 static void decon_ctx_remove(struct decon_context *ctx)
 {
 	/* detach this sub driver from iommu mapping if supported. */
-	if (is_drm_iommu_supported(ctx->drm_dev))
-		drm_iommu_detach_device(ctx->drm_dev, ctx->dev);
+	drm_iommu_detach_device(ctx->drm_dev, ctx->dev);
 }
 
 static u32 decon_calc_clkdiv(struct decon_context *ctx,