Clean-up of 2 parts in the ISP code that are redundant

Clean-up of 2 parts in the ISP code that are redundant. The changes do not alter the performance in any way, i.e., the results are exactly the same.

1. In the full RD intra mode tests loop (estIntraPredLumaQT) there is the following condition: if ( uiOrgMode <= DC_IDX ) -> do X; else-> do X. Since X is the same in both cases, the redundant code has been removed.

2. In xRecurIntraCodingLumaQT there is the threshold definition

double threshold = nSubPartitions == 2 ? 0.95 : subTuCounter == 0 ? 0.67 : subTuCounter == 1 ? 0.83 : 0.91;

Since subTuCounter can never be 0 (it is at least 1) at the time this expression is evaluated, the code has been simplified in the following way:

double threshold = nSubPartitions == 2 ? 0.95 : subTuCounter == 1 ? 0.83 : 0.91;