migration: Remove redundant cleanup of postcopy_qemufile_src

This file is owned by the return path thread which is already doing
cleanup.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230918172822.19052-6-farosas@suse.de>

migration/migration.c

@@ -1178,12 +1178,6 @@ static void migrate_fd_cleanup(MigrationState *s)
         qemu_fclose(tmp);
     }
 
-    if (s->postcopy_qemufile_src) {
-        migration_ioc_unregister_yank_from_file(s->postcopy_qemufile_src);
-        qemu_fclose(s->postcopy_qemufile_src);
-        s->postcopy_qemufile_src = NULL;
-    }
-
     assert(!migration_is_active(s));
 
     if (s->state == MIGRATION_STATUS_CANCELLING) {