This commit changes files in src/python/gem5 so that memory and
cache sizes use "KiB", "MiB", and "GiB" instead of "KB", etc. This
makes the codebase more consistent, as gem5 will automatically
convert memory and cache sizes that are in metric units (KB) to
binary units (KiB).
Change-Id: If5b1e908ddcff7182b71e789229a3ba1fa6ad1f1