misc: Use variables directly in format! string

Fix clippy warning `uninlined_format_args` reported by rustc rustc
1.89.0 (29483883e 2025-08-04).

```console
warning: variables can be used directly in the `format!` string
   --> block/src/lib.rs:649:17
    |
649 |                 info!("{} failed to create io_uring instance: {}", error_msg, e);
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
    = note: `#[warn(clippy::uninlined_format_args)]` on by default
help: change this to
    |
649 -                 info!("{} failed to create io_uring instance: {}", error_msg, e);
649 +                 info!("{error_msg} failed to create io_uring instance: {e}");
    |
```

Signed-off-by: Ruoqing He <heruoqing@iscas.ac.cn>

devices/src/legacy/cmos.rs

@@ -90,7 +90,7 @@ impl BusDevice for Cmos {
                     self.data[(self.index & INDEX_MASK) as usize] = data[0]
                 }
             }
-            o => warn!("bad write offset on CMOS device: {}", o),
+            o => warn!("bad write offset on CMOS device: {o}"),
         };
         None
     }
@@ -164,7 +164,7 @@ impl BusDevice for Cmos {
                 }
             }
             o => {
-                warn!("bad read offset on CMOS device: {}", o);
+                warn!("bad read offset on CMOS device: {o}");
                 0
             }
         }

devices/src/legacy/i8042.rs

@@ -45,7 +45,7 @@ impl BusDevice for I8042Device {
         if data.len() == 1 && data[0] == 0xfe && offset == 3 {
             info!("i8042 reset signalled");
             if let Err(e) = self.reset_evt.write(1) {
-                error!("Error triggering i8042 reset event: {}", e);
+                error!("Error triggering i8042 reset event: {e}");
             }
             // Spin until we are sure the reset_evt has been handled and that when
             // we return from the KVM_RUN we will exit rather than re-enter the guest.