HOWTO: fix unit type suffix in "Parameter types" section to upper case

Redo 9ff84231('HOWTO: fix unit type suffix in "Parameter types" section').

> These should be all in lower case or all in upper case, but not both.
> The man page already has these in lower case.

Change above to all upper case based on below comment, instead of all
in lower. Fix the man page (which originally had in lower) as well.

RE: [PATCH 2/4] HOWTO: fix unit type suffix in "Parameter types" section
http://www.spinics.net/lists/fio/msg06146.html
Signed-off-by: Tomohiro Kusumi <tkusumi@tuxera.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>