USB: gadget: udc: s3c2410_udc: fix return value check in s3c2410_udc_probe()

In case of error, the function devm_platform_ioremap_resource()
returns ERR_PTR() and never returns NULL. The NULL test in the
return value check should be replaced with IS_ERR().

Fixes: 188db443 ("usb: gadget: s3c: use platform resources")
Cc: stable <stable@vger.kernel.org>
Reported-by: NHulk Robot <hulkci@huawei.com>
Reviewed-by: NArnd Bergmann <arnd@arndb.de>
Reviewed-by: NKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20210305034927.3232386-1-weiyongjun1@huawei.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/s3c2410_udc.c

@@ -1773,8 +1773,8 @@ static int s3c2410_udc_probe(struct platform_device *pdev)
 	udc_info = dev_get_platdata(&pdev->dev);
 
 	base_addr = devm_platform_ioremap_resource(pdev, 0);
-	if (!base_addr) {
-		retval = -ENOMEM;
+	if (IS_ERR(base_addr)) {
+		retval = PTR_ERR(base_addr);
 		goto err_mem;
 	}