drm/exynos/mixer: fix interrupt clearing

The driver used incorrect flags to clear interrupt status.
The patch fixes it.
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_mixer.c

@@ -718,6 +718,10 @@ static irqreturn_t mixer_irq_handler(int irq, void *arg)
 
 	/* handling VSYNC */
 	if (val & MXR_INT_STATUS_VSYNC) {
+		/* vsync interrupt use different bit for read and clear */
+		val |= MXR_INT_CLEAR_VSYNC;
+		val &= ~MXR_INT_STATUS_VSYNC;
+
 		/* interlace scan need to check shadow register */
 		if (ctx->interlace) {
 			base = mixer_reg_read(res, MXR_GRAPHIC_BASE(0));
@@ -743,11 +747,6 @@ static irqreturn_t mixer_irq_handler(int irq, void *arg)
 
 out:
 	/* clear interrupts */
-	if (~val & MXR_INT_EN_VSYNC) {
-		/* vsync interrupt use different bit for read and clear */
-		val &= ~MXR_INT_EN_VSYNC;
-		val |= MXR_INT_CLEAR_VSYNC;
-	}
 	mixer_reg_write(res, MXR_INT_STATUS, val);
 
 	spin_unlock(&res->reg_slock);