soundwire: amd: Fix a check for errors in probe()

This code has two problems:
1) The devm_ioremap() function returns NULL, not error pointers.
2) It's checking the wrong variable.  ->mmio instead of ->acp_mmio.

Fixes: d8f48fb ("soundwire: amd: Add support for AMD Manager driver")
Suggested-by: "Mukunda,Vijendar" <vijendar.mukunda@amd.com>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/9863b2bf-0de2-4bf8-8f09-fe24dc5c63ff@moroto.mountain
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: Dan Carpenter

drivers/soundwire/amd_manager.c

@@ -910,9 +910,9 @@ static int amd_sdw_manager_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	amd_manager->acp_mmio = devm_ioremap(dev, res->start, resource_size(res));
-	if (IS_ERR(amd_manager->mmio)) {
+	if (!amd_manager->acp_mmio) {
 		dev_err(dev, "mmio not found\n");
-		return PTR_ERR(amd_manager->mmio);
+		return -ENOMEM;
 	}
 	amd_manager->instance = pdata->instance;
 	amd_manager->mmio = amd_manager->acp_mmio +