dma-coherent: remove an unused variable

Signed-off-by: Christoph Hellwig <[e-mail]>
Reported-by: Stephen Rothwell <[e-mail]>

drivers/base/dma-coherent.c

···
 	int order = get_order(size);
 	unsigned long flags;
 	int pageno;
-	int dma_memory_map;
 	void *ret;
 
 	spin_lock_irqsave(&mem->spinlock, flags);