pci: reevaluate #[allow] attributes

Drop stale #[allow]s whose lints no longer fire and convert the
rest to #[expect], which warns if they ever stop being needed.

Part of #8326.

Signed-off-by: Tushar Khatri <hello@tusharkhatri.in>

pci/src/vfio_user.rs

@@ -73,7 +73,7 @@ impl PciSubclass for PciVfioUserSubclass {
 }
 
 impl VfioUserPciDevice {
-    #[allow(clippy::too_many_arguments)]
+    #[expect(clippy::too_many_arguments)]
     pub fn new(
         id: String,
         vm: Arc<dyn hypervisor::Vm>,