bus unit: Do not zero- or sign-extend 24-bit reads (because those only happen as part of 32-bit reads, meaning the extensions will be overwritten). Cuts down on the logic.
bus unit: Do not zero- or sign-extend 24-bit reads (because those only happen as part of 32-bit reads, meaning the extensions will be overwritten). Cuts down on the logic.

maikmerten/riscv-tomthumb,maikmerten/riscv-tomthumb