drm/amdgpu: only set DP subconnector type on DP and eDP connectors

Fixes a crash in drm_object_property_set_value() because the property
is not set for internal DP ports that connect to a bridge chips
(e.g., DP to VGA or DP to LVDS).

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=210739
Fixes: 65bf2cf95d3ade ("drm/amdgpu: utilize subconnector property for DP through atombios")
Tested-By: Kris Karas <[e-mail]>
Cc: Oleg Vasilev <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>
Cc: [e-mail] # 5.10.x

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

···
 		pm_runtime_put_autosuspend(connector->dev->dev);
 	}
 
-	drm_dp_set_subconnector_property(&amdgpu_connector->base,
-					 ret,
-					 amdgpu_dig_connector->dpcd,
-					 amdgpu_dig_connector->downstream_ports);
+	if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort ||
+	    connector->connector_type == DRM_MODE_CONNECTOR_eDP)
+		drm_dp_set_subconnector_property(&amdgpu_connector->base,
+						 ret,
+						 amdgpu_dig_connector->dpcd,
+						 amdgpu_dig_connector->downstream_ports);
 	return ret;
 }