[ARM] tegra: Add APB DMA support

The APB DMA block handles DMA transfers to and from some peripherals
in the Tegra SOC.  It reads from sequential addresses on the memory
bus, and writes repeatedly to the same address on the APB bus.

Two transfer modes are supported, oneshot for transferring a known
size to or from a peripheral, and continuous for streaming data.
In continuous mode, a callback occurs when the buffer is half full
to allow the existing data to be handled and a new request queued.x

v2 changes:
	dma API no longer uses PTR_ERR

Signed-off-by: Erik Gilling <konkers@android.com>
Signed-off-by: Colin Cross <ccross@android.com>