A DMA hardware can have big cache or FIFO and the amount of data sitting in
the DMA fabric can be an interest for the clients.

For example in audio we want to know the delay in the data flow and in case
the DMA have significantly large FIFO/cache, it can affect the latenc/delay
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Tero Kristo <t-kristo@ti.com>
Tested-by: Keerthy <j-keerthy@ti.com>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Link: https://lore.kernel.org/r/20191223110458.30766-6-peter.ujfalusi@ti.comSigned-off-by: Vinod Koul <vkoul@kernel.org>