Enable AVC VDEnc on BXT
Enable AVC VDEnc on BXT

I verified AVC VDEnc with the HuC loading patch from
https://patchwork.freedesktop.org/api/1.0/series/16584/revisions/1/mbox/

Signed-off-by: Xiang, Haihao <8d677183e5993577d4fa73a419b76987913292d6@intel.com>
Tested-by: Tang, FuweiX <f21b390ec5c26db20c1a6309c43b3f6bfcc11b9b@intel.com>

01org/iotg-lin-gfx-va-driver,01org/iotg-lin-gfx-va-driver,01org/iotg-lin-gfx-va-driver,01org/iotg-lin-gfx-va-driver,01org/iotg-lin-gfx-va-driver