hw/isa/isa-superio: Fix IDE controller realization

hw/isa/isa-superio: Fix IDE controller realization

When realizing a Super I/O with IDE controller [*], we get:

  qom/object.c:1684: object_property_try_add_child: Assertion `!child->parent' failed.
  Aborted (core dumped)

This is because the device is already realized when we try to
add the QOM property to the parent. Fix by realizing *after*
adding the QOM relationship.

[*] Set ISASuperIOClass::ide.count = N with N not zero
    (no such thing currently exists; the bug is latent)

Fixes: e508430619 ("hw/isa/superio: Make the components QOM children")
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200721124516.9602-1-f4bug@amsat.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>