Hi Mushtaq,
The only time these bits need to be programmed is if you are using the headphone detect feature with a given output (in your case HPLCOM/HPRCOM). These bits will set the Mic Detect comparator logic levels to correspond to the usage case in register 38. So if you are using the mic detect pin on these outputs, pseudo diff (D6) would would be set if one COM output was set to VCM, D3 would be set if the COM output is set to differential.