TimeSlewSim fix for 74X

Fixes the bug introduced in HCAL digitization in 730pre2, which affects high-energy part of the spectrum (rechits with > 1 TeV in HB/HE, reducing their energy by factor 3-4). Not visible in regular QCD and TTbar samples, only noticeable in QCD_Pt_3000-3500 RelVal.

Private very-high-energy single-pion gun event-by-event tests and re-digi/re-reco of QCD_Pt_3000-3500 RelVal:
http://hep.baylor.edu/cmshcal/Validation/MC/730pre3_MCRUN2_73_V5-v1_TimeSlewFix_vs_730pre3_MCRUN2_73_V5-v1_noChange_RelVal/HighPtQCD/RecHits/RecHits_energy_HB.gif
show that the bug is fixed.