removed unnecessary mutables from CondFormats/L1TObjects

The mutables were being flagged by the static analyzer as thread
safety issues. Turns out the mutables were not needed since no
const member functions ever modified the values.
Merge pull request #4160 from Dr15Jones/removeUnneededMutableCondFormatsL1TObjects

removed unnecessary mutables from CondFormats/L1TObjects
Merge remote branch 'origin/CMSSW_7_1_X' into CMSSW_7_0_X