MIPS: jz4740: Register jz4740 DMA device

Register a device for the newly added jz4740 dmaengine driver.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
[manually edited to align struct assignment]
Signed-off-by: Vinod Koul <vinod.koul@intel.com>