Fix for ring hung issue in SNB platform.

This issue is trigger by the fixed from
commit id: 7deaf55
use to fix segmentation fault issue by checking dst_object->bo
is NULL and VA_STATUS_ERROR_UNIMPLEMENTED in i965_proc_picture_fast
function will causing GPU hung in ring.

By disable the PPGTT, no more GPU hang issue.

If return VA_STATUS_ERROR_INVALID_SURFACE for checking only
dst_obj->bo is NULL, it is working fine without purposely to
disable PPGTT.

End up decided to use VA_STATUS_ERROR_INVALID_SURFACE instead
VA_STATUS_ERROR_UNIMPLEMENTED for dst_obj->bo checking in
i965_proc_picture_fast.

Signed-off-by: Lim Siew Hoon <siew.hoon.lim@intel.com>
Reviewed-by: Kelley, Sean V" <sean.v.kelley@intel.com>

src/i965_post_processing.c

@@ -5724,7 +5724,7 @@ i965_proc_picture_fast(VADriverContextP ctx,
         return VA_STATUS_ERROR_INVALID_SURFACE;
 
     if (!dst_obj_surface->bo)
-        return VA_STATUS_ERROR_UNIMPLEMENTED;
+        return VA_STATUS_ERROR_INVALID_SURFACE;
 
     if (dst_obj_surface->fourcc &&
         dst_obj_surface->fourcc != src_obj_surface->fourcc)