dmaengine: convert drivers/dma/* to use module_platform_driver()

This patch converts the drivers in drivers/dma/* to use the
module_platform_driver() macro which makes the code smaller and a bit
simpler.

Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Piotr Ziecik <kosmo@semihalf.com>
Cc: Rongjun Ying <rongjun.ying@csr.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Pelagicore AB <info@pelagicore.com>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>