Logically until we have handled the first operation the latency is
infinite; this logic was applied to the minimum latency originally but
this patch extends that logic to the maximum and average latency.
To prevent the initial average latency being skewed by the inclusion of
infinity the average value is initally seeded with the first measured
latency.
Fixes: #5704
Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
b5766028a8