drm/exynos: decon5433: Fix per-plane global alpha for XRGB modes

Set per-plane global alpha to maximum value to get proper blending of
XRGB and ARGB planes. This fixes the strange order of overlapping planes.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos5433_drm_decon.c

@@ -356,8 +356,8 @@ static void decon_update_plane(struct exynos_drm_crtc *crtc,
 		writel(val, ctx->addr + DECON_VIDOSDxB(win));
 	}
 
-	val = VIDOSD_Wx_ALPHA_R_F(0x0) | VIDOSD_Wx_ALPHA_G_F(0x0) |
-		VIDOSD_Wx_ALPHA_B_F(0x0);
+	val = VIDOSD_Wx_ALPHA_R_F(0xff) | VIDOSD_Wx_ALPHA_G_F(0xff) |
+		VIDOSD_Wx_ALPHA_B_F(0xff);
 	writel(val, ctx->addr + DECON_VIDOSDxC(win));
 
 	val = VIDOSD_Wx_ALPHA_R_F(0x0) | VIDOSD_Wx_ALPHA_G_F(0x0) |