Perform the same clean commit b2516f7af9d2 ("rust: kernel: remove
`#[allow(clippy::new_ret_no_self)]`") did for a case that appeared in
workqueue in parallel in commit 7324b88975c5 ("rust: workqueue: add
helper for defining work_struct fields"):
Clippy triggered a false positive on its `new_ret_no_self` lint
when using the `pin_init!` macro. Since Rust 1.67.0, that does
not happen anymore, since Clippy learnt to not warn about
`-> impl Trait<Self>` [1][2].
The kernel nowadays uses Rust 1.72.1, thus remove the `#[allow]`.