VME uses reference frame parsed from slice_param instead of hacked DPB for Gen8
VME uses reference frame parsed from slice_param instead of hacked DPB for Gen8

This is backported from Ivy/Haswell/Sandybridge.

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

01org/iotg-lin-gfx-va-driver,gbeauchesne/libva-intel-driver,chenxianqin/vaapi-intel-driver,chenxianqin/vaapi-intel-driver,01org/iotg-lin-gfx-va-driver,uartie/vaapi-intel-driver,01org/iotg-lin-gfx-va-driver,chenxianqin/vaapi-intel-driver,01org/iotg-lin-gfx-va-driver,uartie/vaapi-intel-driver,uartie/vaapi-intel-driver,uartie/vaapi-intel-driver,chenxianqin/vaapi-intel-driver,gbeauchesne/libva-intel-driver,gbeauchesne/libva-intel-driver,chenxianqin/vaapi-intel-driver,gbeauchesne/libva-intel-driver,01org/iotg-lin-gfx-va-driver,uartie/vaapi-intel-driver,gbeauchesne/libva-intel-driver