pata_qdi: Fix initialisation

The QDI init code contains some bugs which mean it only works if you have
a test setup that causes both a successful and failed probe. Fix this

Found by Philip Guo

(Who found it working on code analysis tools not running VLB IDE
controllers)

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>