qcom-sps-dma: DMA-engine driver for BAM using sps API

qcom-sps-dma driver provides DMA-engine interface for the
sps-BAM driver. This driver enables external bus drivers
to replace the underlying DMA HW seamlessly.

The client drivers are responsible for setting clocks on,
before calling DMA services. On a client call,
qcom-sps-dma checks if the BAM device is initialized,
and if it is not, it initializes it before handling
transfers.

Clients configure their DMA channels by adding dmas and
dma-names in their device tree nodes, and use a phandle
to point to the required qcom-sps-dma instance. Before
using that channels, clients are required to configure them
with the DMA transfer direction.

Change-Id: I15279cc57fed7c93b4a36e29de73dd617da76186
Signed-off-by: Gilad Avidov <gavidov@codeaurora.org>
Signed-off-by: Ankit Gupta <ankgupta@codeaurora.org>
Signed-off-by: Sandya Chikka <sandyachikka@codeaurora.org>