ASoC: qdsp6: Fix an IS_ERR() vs NULL bug

The function gpr_alloc_port return ERR_PTR on errors, it doesn't return
null.
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Link: https://lore.kernel.org/r/20211211065840.1221-1-linmq006@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/qcom/qdsp6/q6apm.c

@@ -630,9 +630,9 @@ struct q6apm_graph *q6apm_graph_open(struct device *dev, q6apm_cb cb,
 	init_waitqueue_head(&graph->cmd_wait);
 
 	graph->port = gpr_alloc_port(apm->gdev, dev, graph_callback, graph);
-	if (!graph->port) {
+	if (IS_ERR(graph->port)) {
 		kfree(graph);
-		ret = -ENOMEM;
+		ret = PTR_ERR(graph->port);
 		goto err;
 	}