sysbus: remove outdated comment

The init callback is no more since commit
817a17fc60f44e29a1944b60d32f45ea127f0cf9 ("core/sysbus: remove the
SysBusDeviceClass::init path")

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

include/hw/sysbus.h

@@ -24,10 +24,6 @@ typedef struct SysBusDevice SysBusDevice;
 
 /**
  * SysBusDeviceClass:
- * @init: Callback function invoked when the #DeviceState.realized property
- * is changed to %true. Deprecated, new types inheriting directly from
- * TYPE_SYS_BUS_DEVICE should use #DeviceClass.realize instead, new leaf
- * types should consult their respective parent type.
  *
  * SysBusDeviceClass is not overriding #DeviceClass.realize, so derived
  * classes overriding it are not required to invoke its implementation.