chromium_mod: First convert then slice

More efficient. Highlighted by new clippy lint:

```
error: calling `as_bytes` after slicing a string
   --> framework_lib/src/chromium_ec/mod.rs:919:45
    |
919 |         request.name[..end].copy_from_slice(name[..end].as_bytes());
    |                                             ^^^^^^^^^^^^^^^^^^^^^^ help: try: `&name.as_bytes()[..end]`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#sliced_string_as_bytes
    = note: `-D clippy::sliced-string-as-bytes` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::sliced_string_as_bytes)]`
```

Signed-off-by: Daniel Schaefer <dhs@frame.work>

Author: JohnAZoidberg

framework_lib/src/chromium_ec/mod.rs

@@ -916,7 +916,7 @@ impl CrosEc {
         let mut request = EcRequestGpioGetV0 { name: [0; MAX_LEN] };
 
         let end = MAX_LEN.min(name.len());
-        request.name[..end].copy_from_slice(name[..end].as_bytes());
+        request.name[..end].copy_from_slice(&name.as_bytes()[..end]);
 
         let res = request.send_command(self)?;
         Ok(res.val == 1)