drm/imx: drm_dev_alloc() returns error pointers

We are checking for NULL here, when we should be checking for error
pointers.

Fixes: 54db5decce17 ("drm/imx: drop deprecated load/unload drm_driver ops")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/drm/imx/imx-drm-core.c

@@ -357,8 +357,8 @@ static int imx_drm_bind(struct device *dev)
 	int ret;
 
 	drm = drm_dev_alloc(&imx_drm_driver, dev);
-	if (!drm)
-		return -ENOMEM;
+	if (IS_ERR(drm))
+		return PTR_ERR(drm);
 
 	imxdrm = devm_kzalloc(dev, sizeof(*imxdrm), GFP_KERNEL);
 	if (!imxdrm) {