Updated HCAL validation for SLHC

By default "regular" (non-SLHC) mode is set.

SLHC mode requires the following customization:
src/SLHCUpgradeSimulations/Configuration/python/HCalCustoms.py

def customise_Validation(process):
    process.validation_step.remove(process.AllHcalDigisValidation)
    process.validation_step.remove(process.RecHitsValidation)
    process.validation_step.remove(process.globalhitsanalyze)
    return process
-> 
def customise_Validation(process):
    process.AllHcalDigisValidation.doSLHC = True
    process.RecHitsValidation.doSLHC = True
    process.validation_step.remove(process.globalhitsanalyze)
    return process