pl050: introduce PL050DeviceClass for the PL050 device

This will soon be used to store the reference to the PL050 parent device
for PL050_KBD_DEVICE and PL050_MOUSE_DEVICE.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Helge Deller <deller@gmx.de>
Acked-by: Helge Deller <deller@gmx.de>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20220712215251.7944-8-mark.cave-ayland@ilande.co.uk>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
diff --git a/hw/input/pl050.c b/hw/input/pl050.c
index e32d860..d7796b7 100644
--- a/hw/input/pl050.c
+++ b/hw/input/pl050.c
@@ -216,6 +216,8 @@
     .parent        = TYPE_SYS_BUS_DEVICE,
     .instance_init = pl050_init,
     .instance_size = sizeof(PL050State),
+    .class_init    = pl050_class_init,
+    .class_size    = sizeof(PL050DeviceClass),
     .abstract      = true,
     .class_init    = pl050_class_init,
 };