Consolidate the setup of the channel control register.  Prepare the
basic value in the preparation of the DMA descriptor, and write it into
the register upon descriptor execution.
Acked-by: NTony Lindgren <tony@atomide.com>
Acked-by: NVinod Koul <vinod.koul@intel.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>