rust: error: modify `from_errno` to use `try_from_errno`

Modify the from_errno function to use try_from_errno to
reduce code duplication while still maintaining all existing
behavior and error handling and also reduces unsafe code.

Link: https://github.com/Rust-for-Linux/linux/issues/1125


Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Co-developed-by: Guilherme Augusto Martins da Silva <guilhermev2huehue@gmail.com>
Signed-off-by: Guilherme Augusto Martins da Silva <guilhermev2huehue@gmail.com>
Signed-off-by: Daniel Sedlak <daniel@sedlak.dev>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Link: https://lore.kernel.org/r/20241207112445.55502-1-daniel@sedlak.dev


Signed-off-by: Miguel Ojeda <ojeda@kernel.org>