man: fix mandoc lint errors

man: fix mandoc lint errors

Fix the most egregious warnings produced by running
mandoc -W warning,stop ./fio.1 > /dev/null

- Fix usage of .RE when .RS block isn't open
- Stop escaping = as it's not needed
- Fix incorrect usage .TP before .RE as the line following .TP isn't a
  leading tag and it is having no effect
- Fix broken macro sequence and incorrect usage of \fR...\fP which
  should have been \fB...\fP because it's outside of .BI

Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>