dmaengine: xilinx_dma: Refactor axidma channel allocation

In axidma alloc_chan_resources merge BD and cyclic BD allocation.

Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>