Apply "sar -d" changes to sadf

Apply "sar -d" changes to sadf

Replace "rd_sec/s" and "wr_sec/s" fields  (expressed in sectors) with
"rkB/s" and "wkB/s" (expressed in kilobytes).
Replace "avgrq-sz" field (expressed in sectors) with "areq-sz" (expressed
in kilobytes).

Rename "avgqu-sz" field to "aqu-sz".

Original field names are still present in sadf's XML and JSON output to
keep backward compatibility.

Signed-off-by: Sebastien GODARD <sysstat@users.noreply.github.com>