dma: Add a jz4740 dmaengine driver

This patch adds dmaengine support for the JZ4740 DMA controller. For now the
driver will be a wrapper around the custom JZ4740 DMA API. Once all users of the
custom JZ4740 DMA API have been converted to the dmaengine API the custom API
will be removed and direct hardware access will be added to the dmaengine
driver.

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