PGPE: Use correct VPD Pts for VDD to Pstate intp.

    Key_Cronus_Test=PM_REGRESS

Change-Id: Ie33bbeaed17b936845dcdc75874d149ca6693e37
CQ: SW446944
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/66812
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Reviewed-by: Jennifer A. Stofer <stofer@us.ibm.com>

import/chips/p9/procedures/ppe_closed/pgpe/pstate_gpe/p9_pgpe_gppb.c

@@ -155,7 +155,7 @@ uint8_t p9_pgpe_gppb_intp_ps_from_ext_vdd(uint16_t ext_vdd)
     //Do the math using shifted by 1.
     ps = -(((G_gppb->VPStateSlopes[VPD_PT_SET_BIASED_SYSP][r]) *
             (ext_vdd - G_gppb->operating_points_set[VPD_PT_SET_BIASED_SYSP][r].vdd_mv)) >> (VID_SLOPE_FP_SHIFT_12 - 1)) +
-         (G_gppb->operating_points_set[VPD_SLOPES_BIASED][r].pstate << 1)  ;
+         (G_gppb->operating_points_set[VPD_PT_SET_BIASED_SYSP][r].pstate << 1)  ;
     ps = ps >> 1;//Shift it back
 
     return ps;