ASoC: sof: Fix warning when IPC flood test is not enabled

dentry is only used when the flood test is done so move the declaration
of the variable inside the ifdef for the flood test.

Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/debug.c

@@ -221,7 +221,6 @@ static ssize_t sof_dfsentry_read(struct file *file, char __user *buffer,
 {
 	struct snd_sof_dfsentry *dfse = file->private_data;
 	struct snd_sof_dev *sdev = dfse->sdev;
-	struct dentry *dentry;
 	loff_t pos = *ppos;
 	size_t size_ret;
 	int skip = 0;
@@ -229,6 +228,8 @@ static ssize_t sof_dfsentry_read(struct file *file, char __user *buffer,
 	u8 *buf;
 
 #if IS_ENABLED(CONFIG_SND_SOC_SOF_DEBUG_IPC_FLOOD_TEST)
+	struct dentry *dentry;
+
 	dentry = file->f_path.dentry;
 	if ((!strcmp(dentry->d_name.name, "ipc_flood_count") ||
 	     !strcmp(dentry->d_name.name, "ipc_flood_duration_ms")) &&