DMA: PL330: Add device tree support

For PL330 dma controllers instantiated from device tree, the channel
lookup is based on phandle of the dma controller and dma request id
specified by the client node. During probe, the private data of each
channel of the controller is set to point to the device node of the
dma controller. The 'chan_id' of the each channel is used as the
dma request id.

Client driver requesting dma channels specify the phandle of the
dma controller and the request id. The pl330 filter function
converts the phandle to the device node pointer and matches that
with channel's private data. If a match is found, the request id
from the client node and the 'chan_id' of the channel is matched.
A channel is found if both the values match.

Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
Acked-by: Boojin Kim <boojin.kim@samsung.com>
Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Reviewed-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>