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/timb_dma.c b/drivers/dma/timb_dma.c
index d142ae1..a6f9c16 100644
--- a/drivers/dma/timb_dma.c
+++ b/drivers/dma/timb_dma.c
@@ -841,17 +841,7 @@
 	.remove	= __exit_p(td_remove),
 };
 
-static int __init td_init(void)
-{
-	return platform_driver_register(&td_driver);
-}
-module_init(td_init);
-
-static void __exit td_exit(void)
-{
-	platform_driver_unregister(&td_driver);
-}
-module_exit(td_exit);
+module_platform_driver(td_driver);
 
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("Timberdale DMA controller driver");