dev: Added new LupIO-RNG device

This device is a random number generator that uses the Mersenne
Twister in order to provide the system with a set of random
numbers.  It is implemented as a BasicPioDevice, and has both
read and write capabilities.

The following are the specifications regarding the LupIO-RNG:
https://gitlab.com/luplab/lupio/lupio-specs/-/blob/main/lupio-rng.md

Change-Id: Ia6aeb610ebe5589ed1f1548b823c5165236b03e6
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/53029
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
4 files changed