Fix touchpad by blacklisting AMD SFH driver

Based on dmesg analysis, found that:
- ITE8353 touchpad is detected but bound to hid-sensor-hub
- AMD Sensor Fusion Hub (amd_sfh) is interfering with touchpad
- Error: 'pcie_mp2_amd 0000:02:00.7: amd_sfh_hid_client_init failed err -95'

Blacklisting amd_sfh module should allow touchpad to work properly.

machines/little-rascal/hardware-configuration.nix

@@ -36,6 +36,12 @@
       "i2c_hid"
       "i2c_hid_acpi"
     ];
+    
+    # Blacklist AMD SFH which interferes with touchpad
+    blacklistedKernelModules = [
+      "amd_sfh"  # AMD Sensor Fusion Hub - causes touchpad to be misidentified
+    ];
+    
     extraModulePackages = [];
   };