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 <[e-mail]>
Tested-by: Linus Walleij <[e-mail]>
Reviewed-by: Linus Walleij <[e-mail]>
Acked-by: Jassi Brar <[e-mail]>
[imx-sdma.c & mxs-dma.c]
Tested-by: Shawn Guo <[e-mail]>
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/mv_xor.c

···
 
 	last_used = chan->cookie;
 	last_complete = mv_chan->completed_cookie;
-	mv_chan->is_complete_cookie = cookie;
 	dma_set_tx_state(txstate, last_complete, last_used, 0);
 
 	ret = dma_async_is_complete(cookie, last_complete, last_used);

drivers/dma/mv_xor.h

···
 #ifdef USE_TIMER
 	unsigned long		cleanup_time;
 	u32			current_on_last_cleanup;
-	dma_cookie_t		is_complete_cookie;
 #endif
 };