kernel: sched_ext: bpf_iter_scx_dsq_new() should always initialize iterator

In the Linux kernel, the following vulnerability has been resolved: schedext: bpfiterscxdsqnew should always initialize iterator BPF programs may call next and destroy on BPF iterators even after new returns an error value e.g. bpfforeach macro ignores error returns from new. bpfiterscxdsqnew cou...