The kernel fmt! proc macro wraps each format argument as &(arg). Passing a
tuple such as (a, b) produces &((a, b)) after expansion. Clippy flags that
as double_parens, but it is a false positive fixed in Clippy 1.92 [1] [2].
Suppress the warning on the affected doctest function with a reason
attribute so it can be removed once the minimum toolchain moves past 1.92.
[ We may end up deciding to support per-version Clippy lints, in which
case we will need [3].
In the future, if [4] gets fixed, we may be able to use
`Delimiter::None` as Gary suggested in [5].