rust: pci: use kernel::fmt

Reduce coupling to implementation details of the formatting machinery by
avoiding direct use for `core`'s formatting traits and macros.

This backslid in commit ed78a01 ("rust: pci: provide access to PCI
Class and Class-related items").

Acked-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Link: https://patch.msgid.link/20251018-cstr-core-v18-8-9378a54385f8@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: tamird

rust/kernel/pci/id.rs

@@ -4,8 +4,7 @@
 //!
 //! This module contains PCI class codes, Vendor IDs, and supporting types.
 
-use crate::{bindings, error::code::EINVAL, error::Error, prelude::*};
-use core::fmt;
+use crate::{bindings, error::code::EINVAL, error::Error, fmt, prelude::*};
 
 /// PCI device class codes.
 ///