rust: kernel: remove compile_fail TODOs

This is part of the effort to minimize the differences of the `rust`
branch with respect to mainline in order to eventually drop it.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: ojeda

rust/kernel/build_assert.rs

@@ -43,7 +43,6 @@ macro_rules! build_error {
 /// These examples show that different types of [`assert!`] will trigger errors
 /// at different stage of compilation. It is preferred to err as early as
 /// possible, so [`static_assert!`] should be used whenever possible.
-// TODO: Could be `compile_fail` when supported.
 /// ```ignore
 /// fn foo() {
 ///     static_assert!(1 > 1); // Compile-time error

rust/kernel/std_vendor.rs

@@ -101,7 +101,6 @@
 ///
 /// The `dbg!(..)` macro moves the input:
 ///
-// TODO: Could be `compile_fail` when supported.
 /// ```ignore
 /// /// A wrapper around `usize` which importantly is not Copyable.
 /// #[derive(Debug)]