dma: pl330: Support per channel irq allocation

Some pl330 have per channel irq and it is necessary
to allocate all of them. Loop over irq assigned for this
device to support these pl330 IPs.

For example this IP is available on Xilinx Zynq platform.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Tested-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>