Add support for selecting dt based on id and rev

Apply mailing list patches from https://lore.kernel.org/all/20191129192919.27715-1-erosca@de.adit-jv.com/T/#r9f56d47be0ecaf7589f79ffe5c2251d4aca15fb0 to use id and rev instead of just index to specify dt from dtimage. This would prevent an incorrect dtb from being loaded if the dtimage is improperly formed, as it would select based on hw revision/sku instead of just the order within the image. This also simplifies Android dev prior to mariko dt release, as dummy dtb's don't need to be copied it it can compile a dtimage with less than the full array of skus.