remoteproc: mediatek: Don't attempt to remap l1tcm memory if missing

The current code doesn't check whether platform_get_resource_byname()
succeeded to get the l1tcm memory, which is optional, before attempting
to map it. This results in the following error message when it is
missing:

  mtk-scp 10500000.scp: error -EINVAL: invalid resource (null)

Add a check so that the remapping is only attempted if the memory region
exists. This also allows to simplify the logic handling failure to
remap, since a failure then is always a failure.

Fixes: ca23ecf ("remoteproc/mediatek: support L1TCM")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20240627-scp-invalid-resource-l1tcm-v1-1-7d221e6c495a@collabora.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

Author: nfraprado

drivers/remoteproc/mtk_scp.c

@@ -1344,14 +1344,12 @@ static int scp_probe(struct platform_device *pdev)
 
 	/* l1tcm is an optional memory region */
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "l1tcm");
-	scp_cluster->l1tcm_base = devm_ioremap_resource(dev, res);
-	if (IS_ERR(scp_cluster->l1tcm_base)) {
-		ret = PTR_ERR(scp_cluster->l1tcm_base);
-		if (ret != -EINVAL)
-			return dev_err_probe(dev, ret, "Failed to map l1tcm memory\n");
+	if (res) {
+		scp_cluster->l1tcm_base = devm_ioremap_resource(dev, res);
+		if (IS_ERR(scp_cluster->l1tcm_base))
+			return dev_err_probe(dev, PTR_ERR(scp_cluster->l1tcm_base),
+					     "Failed to map l1tcm memory\n");
 
-		scp_cluster->l1tcm_base = NULL;
-	} else {
 		scp_cluster->l1tcm_size = resource_size(res);
 		scp_cluster->l1tcm_phys = res->start;
 	}