udev-shim: Only log hotplug events when device count changes

Track the last PCI device count and only emit log messages when
devices are added or removed, eliminating redundant 2-second poll
noise.

local/recipes/system/udev-shim/source/src/main.rs

@@ -129,13 +129,22 @@ fn main() {
     let scheme = Arc::new(Mutex::new(scheme));
     let scheme_clone = Arc::clone(&scheme);
     thread::spawn(move || {
+        let mut last_count = 0usize;
         loop {
             thread::sleep(Duration::from_secs(2));
             if let Ok(mut s) = scheme_clone.lock() {
                 match s.scan_pci_devices() {
-                    Ok(n) if n > 0 => info!("udev-shim: hotplug detected {} device(s)", n),
+                    Ok(n) => {
+                        if n != last_count {
+                            if n > last_count {
+                                info!("udev-shim: hotplug detected {} device(s) (total {})", n - last_count, n);
+                            } else {
+                                info!("udev-shim: device removal detected, {} device(s) remaining", n);
+                            }
+                            last_count = n;
+                        }
+                    }
                     Err(e) => error!("udev-shim: hotplug scan failed: {}", e),
-                    _ => {}
                 }
             }
         }