t/io_uring: show IOPS in increments of 1000 IOPS if necessary

t/io_uring: show IOPS in increments of 1000 IOPS if necessary

It's a bit hard to read the millions of IOPS, so if we're above 100K
IOPS, scale by 1000 and add a K instead. This is easier to read:

IOPS=7235K, BW=3532MiB/s, IOS/call=31/31, inflight=(78 114)
IOPS=7218K, BW=3524MiB/s, IOS/call=32/32, inflight=(79 105)

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