Increase minimum ID_WIDTH

Created by: Silabs-ArjanB

ID_WIDTH is currently specified as being between 1 and 32. Requiring support for ID_WIDTH = 1 causes artificial corner cases already in relatively short pipelines. E.g. a CPU would have to put back pressure on its compressed interface if there is already more than 1 other offloaded instruction in flight (which would be quite normal). Mandating a minimum width of say 3 would allow for 8 in-flight instructions, which would not require a back pressure mechanism to be implemented on normal use cases for the current OpenHW cores that are on the roadmap. On the CPU side this does not imply additional hardware cost as the CPU is still free to only support only 1 or 2 in-flight offloaded instructions (and tie of some MSBs of the ID). On the coprocessor side the increased minimum does imply an increased minimum cost (but not added complexity).