ShellPkg UefiDpLib: Init CustomCumulativeData.MinDur
ShellPkg UefiDpLib: Init CustomCumulativeData.MinDur

Init CustomCumulativeData.MinDur to PERF_MAXDUR, otherwise the
MinDur displayed for custom cumulative data will be always 0,
but not the real shortest duration.

Cc: Liming Gao <6480311aeeb4b006862f6d13ebabddc03f51e507@intel.com>
Cc: Ruiyu Ni <9fa3a6894a36bca79e6a72ad65af5a5702efecd1@intel.com>
Cc: Cinnamon Shia <7442407e887958975262eda9bcd9ed8380ec6899@hpe.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <5c6bb72efe464613af94e84c05522a361b23844a@intel.com>
Reviewed-by: Liming Gao <6480311aeeb4b006862f6d13ebabddc03f51e507@intel.com>

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