Fix Variable Names for P100(Max) Latency in Cachebench

[SuhoSon]

Issue

== Test Results ==
== Allocator Stats ==
...
NVM Read  Latency    p999999  :     10000.00 us
NVM Read  Latency    p100      :    0.00 us
...
NVM Write Latency    p999999  :     10000.00 us
NVM Write Latency    p100      :     0.00 us
...

Debug

Cachelib is using variable name for p100 as max (cachelib/common/PercentileStats.cpp:72). But, Cachebench was using variable name for p100 as p100. So, I have changed Cachebench's variable name to max.

Result

== Test Results ==
== Allocator Stats ==
...
NVM Read  Latency    p999999  :     10000.00 us
NVM Read  Latency    max      :    20000.00 us
...
NVM Write Latency    p999999  :     10000.00 us
NVM Write Latency    max      :     20000.00 us
...