ASoC: SOF: Intel: atom: don't keep a temporary string in fixup_tplg_name

fixup_tplg_name() doesn't need to keep the string, allocated for
filename - it's temporary.

Inspired by similar change for hda:
commit b9088535 ("ASoC: SOF: Intel: HDA: don't keep a temporary variable")
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220715145216.277003-8-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/intel/atom.c

@@ -274,22 +274,22 @@ static const char *fixup_tplg_name(struct snd_sof_dev *sdev,
 				   const char *ssp_str)
 {
 	const char *tplg_filename = NULL;
-	char *filename;
-	char *split_ext;
+	const char *split_ext;
+	char *filename, *tmp;
 
-	filename = devm_kstrdup(sdev->dev, sof_tplg_filename, GFP_KERNEL);
+	filename = kstrdup(sof_tplg_filename, GFP_KERNEL);
 	if (!filename)
 		return NULL;
 
 	/* this assumes a .tplg extension */
-	split_ext = strsep(&filename, ".");
-	if (split_ext) {
+	tmp = filename;
+	split_ext = strsep(&tmp, ".");
+	if (split_ext)
 		tplg_filename = devm_kasprintf(sdev->dev, GFP_KERNEL,
 					       "%s-%s.tplg",
 					       split_ext, ssp_str);
-		if (!tplg_filename)
-			return NULL;
-	}
+	kfree(filename);
+
 	return tplg_filename;
 }