Hi Paramod,
your are right. As you can see in chapter "5.4 Clock definitions" of K70 reference manual, DDR module is clocked by MCGDDRCLK which is the MCG output of the PLL for the DRAM controller. Therefore, if you disable PLL DDR controller is disabled (unclocked).
If you select Int_Flash_SRAMData_Debug configuration it should work.
Regards,
Carlos