Fix for incorrect interpration of HV mapping for endcap presampler (LArHV-00-00-36)

	* src/EMECPresamplerHVManager.cpp   Fix for incorrect interpration of HV mapping for endcap presampler:
           There are 32 modules in phi (0-31)
           each module has 2 cell in phi, in the mapping database this is referred by "gapIndex"
           0 is on the low phi side (in the ATLAS frame)
           1 in on the  high phi side
           so in total 64 sectors in phi given by 2*phiIndex+gapIndex
            the two gap of these sectors are powered by the same line and have the same HV
       (while in the previous code, there were 32 sectors for HV in phi, with the two gaps powered by the two different HV lines)
         * tag LArHV-00-00-36


Former-commit-id: b4b2f949