dmaengine: ti: edma: Do not reset reserved paRAM slots

Skip resetting paRAM slots marked as reserved as they might be used by
other cores.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20190823125618.8133-2-peter.ujfalusi@ti.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>