drm/amdgpu: set external rev id for raven2

It's different from raven1.
Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/soc15.c

@@ -742,6 +742,9 @@ static int soc15_common_early_init(void *handle)
 				AMD_PG_SUPPORT_CP |
 				AMD_PG_SUPPORT_RLC_SMU_HS;
 
+		if (adev->rev_id >= 0x8)
+			adev->external_rev_id = adev->rev_id + 0x81;
+		else
 			adev->external_rev_id = 0x1;
 		break;
 	case CHIP_PICASSO: