PerformancePkg Dp_App: Delete InitCumulativeData()

PerformancePkg Dp_App: Delete InitCumulativeData()

InitCumulativeData is introduced by d28f77df0f51f84b0af79f09abe2c27b1f1aaa69,
it is needed by ShellPkg UefiDpLib, but not needed by PerformancePkg Dp_App.

This patch is to delete it.

Cc: Cinnamon Shia <cinnamon.shia@hpe.com>
Cc: Jaben Carsey <jaben.carsey@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Cinnamon Shia <cinnamon.shia@hpe.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>