dm: implement a DMA uclass

Implement a DMA uclass so that the devices like ethernet, spi,
mmc etc can offload the data transfers from/to the device and
memory.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jagan Teki <jteki@openedev.com>
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index 73cd3ac..3bea308 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -31,6 +31,7 @@
 	UCLASS_CROS_EC,		/* Chrome OS EC */
 	UCLASS_DISK,		/* Disk controller, e.g. SATA */
 	UCLASS_DISPLAY,		/* Display (e.g. DisplayPort, HDMI) */
+	UCLASS_DMA,		/* Direct Memory Access */
 	UCLASS_RAM,		/* RAM controller */
 	UCLASS_ETH,		/* Ethernet device */
 	UCLASS_GPIO,		/* Bank of general-purpose I/O pins */