Fix the error for the VPP conversion of NV12->NV12 on BDW
Fix the error for the VPP conversion of NV12->NV12 on BDW

Signed-off-by: Zhao Yakui <21bae65ecea50a19bd9d0fef489914760189fd5b@intel.com>

halleyzhao/libva-intel-driver-fdo,halleyzhao/libva-intel-driver-fdo,halleyzhao/libva-intel-driver-fdo,halleyzhao/libva-intel-driver-fdo