hw/arm/aspeed: Introduce TYPE_ASPEED2400_SOC

TYPE_ASPEED2400_SOC inherits from TYPE_ASPEED_SOC.
In few commits we'll add more fields, but to keep
review process simple, don't add any yet.

TYPE_ASPEED_SOC is common to various Aspeed SoCs,
define it in aspeed_soc_common.c.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

include/hw/arm/aspeed_soc.h

@@ -101,6 +101,13 @@ struct AspeedSoCState {
 #define TYPE_ASPEED_SOC "aspeed-soc"
 OBJECT_DECLARE_TYPE(AspeedSoCState, AspeedSoCClass, ASPEED_SOC)
 
+struct Aspeed2400SoCState {
+    AspeedSoCState parent;
+};
+
+#define TYPE_ASPEED2400_SOC "aspeed2400-soc"
+OBJECT_DECLARE_SIMPLE_TYPE(Aspeed2400SoCState, ASPEED2400_SOC)
+
 struct Aspeed2600SoCState {
     AspeedSoCState parent;
 };