Pull pin-init updates from Benno Lossin:
- Replace the 'Zeroable' impls for 'Option<NonZero*>' with impls of
'ZeroableOption' for 'NonZero*'.
- Improve feature gate handling for unstable features.
- Declutter the documentation of implementations of 'Zeroable' for
tuples.
- Replace uses of 'addr_of[_mut]!' with '&raw [mut]'.
* tag 'pin-init-v7.1' of https://github.com/Rust-for-Linux/linux:
rust: pin-init: replace `addr_of_mut!` with `&raw mut`
rust: pin-init: implement ZeroableOption for NonZero* integer types
rust: pin-init: doc: de-clutter documentation with fake-variadics
rust: pin-init: properly document let binding workaround
rust: pin-init: build: simplify use of nightly features