hw: arm: allwinner-sramc: Set class_size

AwSRAMCClass is larger than SysBusDeviceClass so the class size must be
advertised accordingly.

Fixes: 05def917e1 ("hw: arm: allwinner-sramc: Add SRAM Controller support for R40")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230628110905.38125-1-akihiko.odaki@daynix.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/misc/allwinner-sramc.c

@@ -159,6 +159,7 @@ static const TypeInfo allwinner_sramc_info = {
     .parent        = TYPE_SYS_BUS_DEVICE,
     .instance_init = allwinner_sramc_init,
     .instance_size = sizeof(AwSRAMCState),
+    .class_size    = sizeof(AwSRAMCClass),
     .class_init    = allwinner_sramc_class_init,
 };