rust: net: use core::ffi::CStr method names

Prepare for `core::ffi::CStr` taking the place of `kernel::str::CStr` by
avoid methods that only exist on the latter.

Link: #1075
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: tamird

rust/kernel/net/phy.rs

@@ -497,7 +497,7 @@ unsafe impl Sync for DriverVTable {}
 pub const fn create_phy_driver<T: Driver>() -> DriverVTable {
     // INVARIANT: All the fields of `struct phy_driver` are initialized properly.
     DriverVTable(Opaque::new(bindings::phy_driver {
-        name: T::NAME.as_char_ptr().cast_mut(),
+        name: crate::str::as_char_ptr_in_const_context(T::NAME).cast_mut(),
         flags: T::FLAGS,
         phy_id: T::PHY_DEVICE_ID.id(),
         phy_id_mask: T::PHY_DEVICE_ID.mask_as_int(),