dmaengine: mv_xor: remove write-only is_complete_cookie

mv_xor's is_complete_cookie is only ever written to, but never read.
This is silly, remove the write-only structure member.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
[imx-sdma.c & mxs-dma.c]
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>

drivers/dma/mv_xor.h

@@ -109,7 +109,6 @@ struct mv_xor_chan {
 #ifdef USE_TIMER
 	unsigned long		cleanup_time;
 	u32			current_on_last_cleanup;
-	dma_cookie_t		is_complete_cookie;
 #endif
 };