add missing units to --examine

add missing units to --examine

Within the output of "mdadm --examine", there are three sizes reported
on adjacent lines. For example:

$ sudo mdadm --examine /dev/md3
[...]
 Avail Dev Size : 17580545024 (8383.06 GiB 9001.24 GB)
     Array Size : 17580417024 (16765.99 GiB 18002.35 GB)
  Used Dev Size : 11720278016 (5588.66 GiB 6000.78 GB)
[...]

This can be confusing, since the first and third line are in 512-byte
sectors, and the second is in KiB.

Add units to avoid ambiguity.

(I don't particularly like the "KiB" notation, but it is at least
unambiguous.)

Signed-off-by: Corey Hickey <bugfood-c@fatooh.org>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>