In PerformanceLib, Identifier is for single PERF, not the pair of PERF.
When find the matched START and END pair, the identifier will not be checked.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>