dma: pl330: Fix cyclic transfers

Allocate a descriptor for each period of a cyclic transfer, not just the first.
Also since the callback needs to be called for each finished period make sure to
initialize the callback and callback_param fields of each descriptor in a cyclic
transfer.

Cc: stable@vger.kernel.org
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>