Move the clnk_ctrl setup to the preparation functions, saving its
value in the omap_desc.  This only needs to be set once per descriptor,
not for each segment, so set it in omap_dma_start_desc() rather than
omap_dma_start().
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>