drm: mxsfb: fix error return code in mxsfb_load()

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170205160036.7364-1-weiyj.lk@gmail.com

drivers/gpu/drm/mxsfb/mxsfb_drv.c

@@ -221,6 +221,7 @@ static int mxsfb_load(struct drm_device *drm, unsigned long flags)
 	mxsfb->fbdev = drm_fbdev_cma_init(drm, 32,
 					  drm->mode_config.num_connector);
 	if (IS_ERR(mxsfb->fbdev)) {
+		ret = PTR_ERR(mxsfb->fbdev);
 		mxsfb->fbdev = NULL;
 		dev_err(drm->dev, "Failed to init FB CMA area\n");
 		goto err_cma;