Refactor print_size() to use a new format_size() helper that formats a size into a buffer. This allows callers to get the formatted string without printing it directly. The format_size() function is only exported in U-Boot proper (controlled by CONFIG_LIB_FORMAT_SIZE) to avoid code-size impact in SPL/TPL where it remains static. Co-developed-by: Claude <noreply@anthropic.com> Signed-off-by: Simon Glass <simon.glass@canonical.com>