Set external_rev_id and disable cg,pg for now.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Feifei Xu <Feifei.Xu@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
                adev->pg_flags = 0;
                adev->external_rev_id = adev->rev_id + 0x14;
                break;
+       case CHIP_VEGA20:
+               adev->cg_flags = 0;
+               adev->pg_flags = 0;
+               adev->external_rev_id = adev->rev_id + 0x28;
+               break;
        case CHIP_RAVEN:
                adev->cg_flags = AMD_CG_SUPPORT_GFX_MGCG |
                        AMD_CG_SUPPORT_GFX_MGLS |