fix out of bound array index in HCalResponse

note:

changed indents causes messy diffs
relevant changes:

FastSimulation/Calorimetry/interface/HCALResponse.h, 
line 90: changed array size

FastSimulation/Calorimetry/src/HCALResponse.cc
line 397: got rid of redundant condition
line 407: only read x1 and x2 when they are actually used