dmaengine: Remove unused definition of DMA_MAX_COOKIE

As of commit commit f04cd407 ("fsldma: fix
controller lockups"), its last (and only ever) user is gone.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>