o Add support for BERI IOMMU device
o Add an experimental IOMMU support to xDMA framework

The BERI IOMMU device is the part of CHERI device-model project [1]. It
translates memory addresses for various BERI peripherals modelled in
software. It accepts FreeBSD/mips64 page directories format and manages
BERI TLB.

1. https://github.com/CTSRD-CHERI/device-model

Sponsored by: DARPA, AFRL