drm/rockchip: fix error check when getting irq

platform_get_irq() can return negative error values and we already test for
these. Therefore the variable holding this value should be signed to not
loose possible error values.
Reported-by: NDavid Binderman <dcb314@hotmail.com>
Signed-off-by: NHeiko Stuebner <heiko@sntech.de>
Reviewed-By: NDaniel Kurtz <djkurtz@chromium.org>

drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -1409,7 +1409,7 @@ static int vop_bind(struct device *dev, struct device *master, void *data)
 	struct vop *vop;
 	struct resource *res;
 	size_t alloc_size;
-	int ret;
+	int ret, irq;
 
 	of_id = of_match_device(vop_driver_dt_match, dev);
 	vop_data = of_id->data;
@@ -1445,11 +1445,12 @@ static int vop_bind(struct device *dev, struct device *master, void *data)
 		return ret;
 	}
 
-	vop->irq = platform_get_irq(pdev, 0);
-	if (vop->irq < 0) {
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
 		dev_err(dev, "cannot find irq for vop\n");
-		return vop->irq;
+		return irq;
 	}
+	vop->irq = (unsigned int)irq;
 
 	spin_lock_init(&vop->reg_lock);
 	spin_lock_init(&vop->irq_lock);