2262: Add comments to hal/src/device.rs r=kvark a=Michael-Lfx

Fixes #issue
PR checklist:
- [ ] `make` succeeds (on *nix)
- [ ] `make reftests` succeeds
- [ ] tested examples with the following backends:
- [ ] `rustfmt` run on changed code


Co-authored-by: Michael-LAI JINFENG <cihv2@163.com>