Allocate IRQ later during probe to avoid code duplication and also
remove the need for weird locking in _probe.
(It was probably there to prevent race with the IRQ handler?)
Signed-off-by: Ondrej Zary <linux@rainbow-software.org> Reviewed-by: Hannes Reinicke <hare@suse.de> Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>