drm/amdgpu: fix the incorrect external id for raven series

This patch fixes the incorrect external id that kernel reports to user mode
driver. Raven2's rev_id is starts from 0x8, so its external id (0x81) should
start from rev_id + 0x79 (0x81 - 0x8). And Raven's rev_id should be 0x21 while
rev_id == 1.
Reported-by: Crystal Jin <Crystal.Jin@amd.com>
Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -729,11 +729,13 @@ static int soc15_common_early_init(void *handle)
 	case CHIP_RAVEN:
 		adev->asic_funcs = &soc15_asic_funcs;
 		if (adev->rev_id >= 0x8)
-			adev->external_rev_id = adev->rev_id + 0x81;
+			adev->external_rev_id = adev->rev_id + 0x79;
 		else if (adev->pdev->device == 0x15d8)
 			adev->external_rev_id = adev->rev_id + 0x41;
+		else if (adev->rev_id == 1)
+			adev->external_rev_id = adev->rev_id + 0x20;
 		else
-			adev->external_rev_id = 0x1;
+			adev->external_rev_id = adev->rev_id + 0x01;
 
 		if (adev->rev_id >= 0x8) {
 			adev->cg_flags = AMD_CG_SUPPORT_GFX_MGCG |