Introduce as_{mut,ref}_unchecked() (feature(ptr_as_ref_unchecked)) #1225
Description
Note: this issue needs to wait until we bump our minimum to Rust 1.85.0, which will happen soon.
as_{mut,ref}_unchecked() (feature(ptr_as_ref_unchecked): rust-lang/rust#122034) has been stabilized in Rust 1.95.0 (rust-lang/rust#151995), and it has been available since Rust 1.80.0 (rust-lang/rust#122492).
Introduce the unstable feature so that everyone can use it (in rust_allowed_features) and use it in a couple places at least to show it (in a second patch, and please do one conversion in the kernel crate and one outside, to show it works in both cases).
This requires submitting a proper patch to the LKML and the Rust for Linux mailing list. Please recall to test your changes (including generating the documentation if changed, running the Rust doctests if changed, etc.), to use a proper title for the commit, to sign your commit under the Developer's Certificate of Origin and to add a Suggested-by: tag, and a Link: tag to this issue. Please see https://docs.kernel.org/process/submitting-patches.html and https://rust-for-linux.com/contributing for details.