[SCSI] qla2xxx: only free_irq() after request_irq() succeeds

If qla2x00_probe_one() fails before calling request_irq() but gets to
qla2x00_free_device() then it will mistakenly try to free an irq it didn't
request.  It's chosing to free based on ha->pdev->irq which is always set.

host->irq is set after request_irq() succeeds so let's use that to decide
to free or not.

This was observed and tested when a silly set of circumstances lead to
firmware loading failing on a 2100.

Signed-off-by: Zach Brown <zach.brown@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>