We now use cpu_pm for saving and restoring device context for deeper SoC
idle states. But for omap3, we must also block idle if SDMA is busy.

If we don't block idle when SDMA is busy, we eventually end up saving and
restoring SDMA register state on PER domain idle while SDMA is active and
that causes at least audio playback to fail.

Fixes: 4c74ecf7 ("dmaengine: ti: omap-dma: Add device tree match data and use it for cpu_pm")
Reported-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20201109154013.11950-1-tony@atomide.comSigned-off-by: Vinod Koul <vkoul@kernel.org>