compiler warning fixes in PWGDIL

compiler warning fixes in PWGDIL. They appear on Mac compilations during CI tests.

analysis/PWGDIL/dielectron/conversion/CbmAnaConversion.cxx
[CTest: warning matched] /Users/fairroot/builds/computing/cbmroot/analysis/PWGDIL/dielectron/conversion/CbmAnaConversion.cxx:1474:35: warning: overlapping comparisons always evaluate to true [-Wtautological-overlap-compare]
          if (grandmotherId != -1 || grandmotherId == -1) {
[CTest: warning suppressed]               ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
[CTest: warning matched] /Users/fairroot/builds/computing/cbmroot/analysis/PWGDIL/dielectron/conversion/CbmAnaConversion.cxx:1468:26: warning: overlapping comparisons always evaluate to true [-Wtautological-overlap-compare]
      if (motherId != -1 || motherId == -1) {
[CTest: warning suppressed]           ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
[CTest: warning suppressed] 2 warnings generated.