Carge clippy complained about:

error: casts from `u8` to `u32` can be expressed infallibly using `From`

So use `From` to convert `u8` to `u32`.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
 rust/hw/timer/hpet/src/hpet.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/hw/timer/hpet/src/hpet.rs b/rust/hw/timer/hpet/src/hpet.rs
index 983f3882f8d3..a3538af14b48 100644
--- a/rust/hw/timer/hpet/src/hpet.rs
+++ b/rust/hw/timer/hpet/src/hpet.rs
@@ -357,7 +357,7 @@ fn update_irq(&mut self, set: bool) {
         // still operate and generate appropriate status bits, but
         // will not cause an interrupt"
         self.get_state()
-            .update_int_status(self.index as u32, set && self.is_int_level_triggered());
+            .update_int_status(u32::from(self.index), set && self.is_int_level_triggered());
         self.set_irq(set);
     }
 
-- 
2.34.1