rust: device_id: replace incorrect word in safety documentation

rust: device_id: replace incorrect word in safety documentation

The safety documentation incorrectly refers to `RawDeviceId` when
transmuting to `RawType`. This fixes the documentation to correctly
indicate that implementers must ensure layout compatibility with
`RawType`, not `RawDeviceId`.

Fixes: 9b90864bb42b ("rust: implement `IdArray`, `IdTable` and `RawDeviceId`")
Signed-off-by: Yilin Chen <1479826151@qq.com>
Link: https://patch.msgid.link/tencent_C18DD5047749311142ED455779C7CCCF3A08@qq.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>