r600: DPH adds w comp of second operand, so set first one to 1 instead

src/mesa/drivers/dri/r600/r700_assembler.c

@@ -2635,7 +2635,7 @@ GLboolean assemble_DOT(r700_AssemblerBase *pAsm)
     }
     else if(pAsm->pILInst[pAsm->uiCurInst].Opcode == OPCODE_DPH) 
     {
-        onecomp_PVSSRC(&(pAsm->S[1].src), 3);
+        onecomp_PVSSRC(&(pAsm->S[0].src), 3);
     } 
 
     if ( GL_FALSE == next_ins(pAsm) )