PRU changed again..

So working with zmatt on irc, we got uio_pruss working again.. (v5.4.x and v5.10.x)

But... By default we load the remoteproc_pruss, to switch to uio_pruss enable this overlay:

```
uboot_overlay_pru=AM335X-PRU-UIO-00A0.dtbo
```

(remoteproc doesn't need an overlay..)