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>
diff --git a/drivers/dma/mpc512x_dma.c b/drivers/dma/mpc512x_dma.c
index 8ba4edc..4d6d4cf 100644
--- a/drivers/dma/mpc512x_dma.c
+++ b/drivers/dma/mpc512x_dma.c
@@ -835,17 +835,7 @@
 	},
 };
 
-static int __init mpc_dma_init(void)
-{
-	return platform_driver_register(&mpc_dma_driver);
-}
-module_init(mpc_dma_init);
-
-static void __exit mpc_dma_exit(void)
-{
-	platform_driver_unregister(&mpc_dma_driver);
-}
-module_exit(mpc_dma_exit);
+module_platform_driver(mpc_dma_driver);
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Piotr Ziecik <kosmo@semihalf.com>");