isa: New isa_new(), isa_realize_and_unref() etc.

I'm converting from qdev_create()/qdev_init_nofail() to
qdev_new()/qdev_realize_and_unref(); recent commit "qdev: New
qdev_new(), qdev_realize(), etc." explains why.

ISA devices use qdev_create() through isa_create() and
isa_try_create().

Provide isa_new(), isa_try_new(), and isa_realize_and_unref() for
converting ISA devices.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200610053247.1583243-19-armbru@redhat.com>
2 files changed