HLE: sceUsb stubs.

Add some stubs for sceUsb.
`auto s = p.Section("sceUsb", 1);` -> `auto s = p.Section("sceUsb", 1, 2);` (increment max version)

```
if (s >= 2) {
   p.Do(usbStarted);
   p.Do(usbConnected);
} else {
   usbStarted = false;
   usbConnected = true;
}
```

Otherwise, old savestates will not be able to load.

-[Unknown]