drm/gma500: Fix error return code in psb_driver_load()

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: 5c49fd3a ("gma500: Add the core DRM files and headers")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20201130020216.1906141-1-zhangjialin11@huawei.com

drivers/gpu/drm/gma500/psb_drv.c

@@ -312,6 +312,8 @@ static int psb_driver_load(struct drm_device *dev, unsigned long flags)
 	if (ret)
 		goto out_err;
 
+	ret = -ENOMEM;
+
 	dev_priv->mmu = psb_mmu_driver_init(dev, 1, 0, 0);
 	if (!dev_priv->mmu)
 		goto out_err;