Align syntax element name from SPS/PPS with specification

cfg/encoder_lowdelay_P_vtm.cfg

cfg/encoder_lowdelay_vtm.cfg

cfg/encoder_randomaccess_vtm.cfg

...nfigExamples/encoder_randomaccess_vtm_RasterScanSlice.cfg

...figExamples/encoder_randomaccess_vtm_RectangularSlice.cfg

...es/encoder_randomaccess_vtm_RectangularSliceFixedSize.cfg

...gExamples/encoder_randomaccess_vtm_SingleTilePerSlice.cfg

source/App/EncoderApp/EncApp.cpp

source/App/EncoderApp/EncAppCfg.cpp

source/App/EncoderApp/EncAppCfg.h

source/Lib/CommonLib/Buffer.cpp

source/Lib/CommonLib/Buffer.h

source/Lib/CommonLib/CodingStatistics.h

source/Lib/CommonLib/CommonDef.h

source/Lib/CommonLib/ContextModelling.cpp

source/Lib/CommonLib/ContextModelling.h

source/Lib/CommonLib/Contexts.cpp

source/Lib/CommonLib/Contexts.h

source/Lib/CommonLib/InterPrediction.cpp

source/Lib/CommonLib/IntraPrediction.cpp