drm/exynos/decon5433: signal frame done interrupt at front porch

DECON in case of video mode generates interrupt by default at start
of vertical back porch. As this interrupt is used to generate VBLANK
events more optimal point is start of vertical front porch.

Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos5433_drm_decon.c

@@ -105,7 +105,7 @@ static int decon_enable_vblank(struct exynos_drm_crtc *crtc)
 		if (ctx->out_type & IFTYPE_I80)
 			val |= VIDINTCON0_FRAMEDONE;
 		else
-			val |= VIDINTCON0_INTFRMEN;
+			val |= VIDINTCON0_INTFRMEN | VIDINTCON0_FRAMESEL_FP;
 
 		writel(val, ctx->addr + DECON_VIDINTCON0);
 	}