dma: pl330: off by one in pl330_probe()

There are only AMBA_NR_IRQS (2) elements in adev->irq[].  This code
maybe works if the there is a zero directly after the array.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>