dmaengine: dw-axi-dmac: move dma_pool_create() to alloc_chan_resources()

dmaengine: dw-axi-dmac: move dma_pool_create() to alloc_chan_resources()

The DMA memory block is created at driver load time and exist for
device lifetime. Move the dma_pool_create() to the ->chan_resource()
callback function allowing the DMA memory blocks to be created as needed
and destroyed when the channel is freed.

Signed-off-by: Sia Jee Heng <jee.heng.sia@intel.com>
Tested-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Link: https://lore.kernel.org/r/20210125013255.25799-4-jee.heng.sia@intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>