devlink: Fix memleak in health diagnose callback

The callback devlink_nl_cmd_health_reporter_diagnose_doit() miss
devlink_fmsg_free(), which leads to memory leak.

Fix it by adding devlink_fmsg_free().

Fixes: e994a75f ("devlink: remove reporter reference counting")
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/1675698976-45993-1-git-send-email-moshe@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/devlink/leftover.c

@@ -6626,18 +6626,22 @@ static int devlink_nl_cmd_health_reporter_diagnose_doit(struct sk_buff *skb,
 
 	err = devlink_fmsg_obj_nest_start(fmsg);
 	if (err)
-		return err;
+		goto out;
 
 	err = reporter->ops->diagnose(reporter, fmsg, info->extack);
 	if (err)
-		return err;
+		goto out;
 
 	err = devlink_fmsg_obj_nest_end(fmsg);
 	if (err)
-		return err;
+		goto out;
+
+	err = devlink_fmsg_snd(fmsg, info,
+			       DEVLINK_CMD_HEALTH_REPORTER_DIAGNOSE, 0);
 
-	return devlink_fmsg_snd(fmsg, info,
-				DEVLINK_CMD_HEALTH_REPORTER_DIAGNOSE, 0);
+out:
+	devlink_fmsg_free(fmsg);
+	return err;
 }
 
 static int