This allows decoders to know that a baseline stream doesn't
contain any of the features that aren't in the constrained
baseline subset.
Set the flags based on what profile we target.
1. In WelsInitSps function, if kuiIntraPeriod is huge, uiLog2MaxFrameNum might be bigger than 15, which may introduce illegal H264 bitstream.
2. if pSvcParm.uiIntraPeriod is not zero (e.g. 14) at the initial, it will init sps.iLog2MaxPocLsb. to 5.
But if I changed pSvcParm.uiIntraPeriod to 40, sps.iLog2MaxPocLsb. is still 5, need to recalcuted this parameter.
(Same with uiLog2MaxFrameNum.)