rust: device: add device name method

rust: device: add device name method

Add a name() method to the `Device` type, which returns a CStr that
contains the device name.

Signed-off-by: Timur Tabi <ttabi@nvidia.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Tested-by: John Hubbard <jhubbard@nvidia.com>
Tested-by: Eliot Courtney <ecourtney@nvidia.com>
Link: https://patch.msgid.link/20260319212658.2541610-2-ttabi@nvidia.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>