dmaengine: tegra210-adma: add pause/resume support

During an audio playback session it is observed that, audio goes off after
few seconds of continuous pause and play. No audio is heard even when the
playback is resumed.

The reason for above is, currently ADMA driver does not handle DMA_PAUSE/
DMA_RESUME and relevant callbacks for dma_device are not implemented. This
patch implements device_pause and device_resume callbacks for the device.
During pause TRANSFER_PAUSE bit of dma channel control register is set and
the same is cleared during resume.

Signed-off-by: Sameer Pujar <spujar@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>