remoteproc: qcom: wcss: Fix return value check in q6v5_wcss_init_mmio()

In case of error, the function devm_ioremap() returns NULL pointer
not ERR_PTR(). The IS_ERR() test in the return value check should
be replaced with NULL test.

Fixes: 0af65b9b ("remoteproc: qcom: wcss: Add non pas wcss Q6 support for QCS404")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20210319094100.4185044-1-weiyongjun1@huawei.comSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/qcom_q6v5_wcss.c

@@ -829,8 +829,8 @@ static int q6v5_wcss_init_mmio(struct q6v5_wcss *wcss,
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "qdsp6");
 	wcss->reg_base = devm_ioremap(&pdev->dev, res->start,
 				      resource_size(res));
-	if (IS_ERR(wcss->reg_base))
-		return PTR_ERR(wcss->reg_base);
+	if (!wcss->reg_base)
+		return -ENOMEM;
 
 	if (wcss->version == WCSS_IPQ8074) {
 		res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rmb");