tools: Add a program to control the SMMUv3TestEngine

A somewhat complicated tool to exercise various features of the SMMU,
using the SMMUv3TestEngine DMA engine. Supports MEMCPY, RAND48 and SUM64
jobs in various shapes and sizes, as well as fault injection and other
useful modes.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Change-Id: I9df4f2f85a9b6527ba5d468e687b7e011ab5616e