qom/object: Fix object_child_foreach_recursive() return value

qom/object: Fix object_child_foreach_recursive() return value

When recursing, the return value of do_object_child_foreach() is not
taken into account.

Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Fixes: d714b8de7747 ("qom: Add recursive version of object_child_for_each")
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200404153340.164861-1-clg@kaod.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>