Handle percentile lists with higher precision that 2 digits

We cap the output at %2.2f right now, that's not always enough.
Make the parser check and store the precision required to
output the list correctly.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Cleanup the percentile output formatting

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Handle normal output wrapping of the percentile list

Signed-off-by: Jens Axboe <axboe@kernel.dk>