migration/multifd: Drop unnecessary helper to destroy IOC

Both socket_send_channel_destroy() and multifd_send_channel_destroy() are
unnecessary wrappers to destroy an IOC, as the only thing to do is to
release the final IOC reference.  We have plenty of code that destroys an
IOC using direct unref() already; keep that style.

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240222095301.171137-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

migration/multifd.c

@@ -659,16 +659,11 @@ static void multifd_send_terminate_threads(void)
     }
 }
 
-static int multifd_send_channel_destroy(QIOChannel *send)
-{
-    return socket_send_channel_destroy(send);
-}
-
 static bool multifd_send_cleanup_channel(MultiFDSendParams *p, Error **errp)
 {
     if (p->c) {
         migration_ioc_unregister_yank(p->c);
-        multifd_send_channel_destroy(p->c);
+        object_unref(OBJECT(p->c));
         p->c = NULL;
     }
     qemu_sem_destroy(&p->sem);

migration/socket.c

@@ -60,13 +60,6 @@ QIOChannel *socket_send_channel_create_sync(Error **errp)
     return QIO_CHANNEL(sioc);
 }
 
-int socket_send_channel_destroy(QIOChannel *send)
-{
-    /* Remove channel */
-    object_unref(OBJECT(send));
-    return 0;
-}
-
 struct SocketConnectData {
     MigrationState *s;
     char *hostname;

migration/socket.h

@@ -23,7 +23,6 @@
 
 void socket_send_channel_create(QIOTaskFunc f, void *data);
 QIOChannel *socket_send_channel_create_sync(Error **errp);
-int socket_send_channel_destroy(QIOChannel *send);
 
 void socket_start_incoming_migration(SocketAddress *saddr, Error **errp);