stm class: Fix module init return on allocation failure

In stm_heartbeat_init(): return value gets reset after the first
iteration by stm_source_register_device(), so allocation failures
after that will, after a clean up, return success. Fix that.

Fixes: 1192918 ("stm class: Add heartbeat stm source device")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Hui <john.wanghui@huawei.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Link: https://lore.kernel.org/r/20210115195917.3184-2-alexander.shishkin@linux.intel.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Wang Hui

drivers/hwtracing/stm/heartbeat.c

@@ -64,16 +64,18 @@ static void stm_heartbeat_unlink(struct stm_source_data *data)
 
 static int stm_heartbeat_init(void)
 {
-	int i, ret = -ENOMEM;
+	int i, ret;
 
 	if (nr_devs < 0 || nr_devs > STM_HEARTBEAT_MAX)
 		return -EINVAL;
 
 	for (i = 0; i < nr_devs; i++) {
 		stm_heartbeat[i].data.name =
 			kasprintf(GFP_KERNEL, "heartbeat.%d", i);
-		if (!stm_heartbeat[i].data.name)
+		if (!stm_heartbeat[i].data.name) {
+			ret = -ENOMEM;
 			goto fail_unregister;
+		}
 
 		stm_heartbeat[i].data.nr_chans	= 1;
 		stm_heartbeat[i].data.link	= stm_heartbeat_link;