Introduce freq_to_str() to convert frequency values in human
friendly units using the SI units for Hertz.
Suggested-by: Luc Michel <luc@lmichel.fr>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Luc Michel <luc@lmichel.fr>
Message-Id: <20201012095804.3335117-2-f4bug@amsat.org>