oRSC BE SPI echo test tracer

Kill printfs via LOG_LEVEL 0, trace execution using address: 0x7FF0

You can check how far the program gets by stoping the program using xmd and then doing:

```
mrd 0x7FF0
```

which will return 0xC, i.e. it crashes here:

https://github.com/ekfriis/cms-calo-layer1/compare/be-spi-echo?expand=1#diff-92278a98eaea9b7fcd5873f908f5bc6aL107