TODO

 1TODO for slave dma
 2
 31. Move remaining drivers to use new slave interface
 42. Remove old slave pointer machansim
 53. Make issue_pending to start the transaction in below drivers
 6	- mpc512x_dma
 7	- imx-dma
 8	- imx-sdma
 9	- mxs-dma.c
10	- intel_mid_dma
114. Check other subsystems for dma drivers and merge/move to dmaengine
125. Remove dma_slave_config's dma direction.