FF: reapply fix from PR #2746 after commit aa123f9 reverted it

When I merged the `OpenFAST/dev` in, I clobbered a change from PR #2746

Author: andrew-platt

glue-codes/fast-farm/src/FAST_Farm_Subs.f90

@@ -789,9 +789,9 @@ SUBROUTINE Farm_InitMD( farm, ErrStat, ErrMsg )
    ALLOCATE( MD_InitInp%PtfmInit(6,farm%p%NumTurbines), MD_InitInp%TurbineRefPos(3,farm%p%NumTurbines), STAT = ErrStat2 )
    if (Failed0("MoorDyn PtfmInit and TurbineRefPos initialization inputs in FAST.Farm.")) return;
 
-   ! gather spatial initialization inputs for Farm-level MoorDyn
+   ! gather spatial initialization inputs for Farm-level MoorDyn (platform locations in their respective coordinate systems and locations of the turbines in the farm global coordinate system)
    DO nt = 1,farm%p%NumTurbines              
-      MD_InitInp%PtfmInit(:,nt) = farm%FWrap(nt)%m%Turbine%MD%m%PtfmInit   ! turbine PRP initial positions and rotations in their respective coordinate systems from each FAST/MD instance
+      MD_InitInp%PtfmInit(:,nt) = farm%FWrap(nt)%m%Turbine%p_FAST%PlatformPosInit ! platform initial positions in their respective coordinate systems from each FAST/ED instance
       MD_InitInp%TurbineRefPos(:,nt) = farm%p%WT_Position(:,nt)            ! reference positions of each turbine in the farm global coordinate system
    END DO