ARM/dma-mapping: remove the dma_coherent member of struct dev_archdata

Since commit ae626eb9 ("ARM/dma-mapping: use dma-direct
unconditionally") only the dma_coherent flag in struct device is used,
so remove the now write only flag in struct dev_archdata.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

arch/arm/include/asm/device.h

@@ -9,7 +9,6 @@ struct dev_archdata {
 #ifdef CONFIG_ARM_DMA_USE_IOMMU
 	struct dma_iommu_mapping	*mapping;
 #endif
-	unsigned int dma_coherent:1;
 	unsigned int dma_ops_setup:1;
 };
 

arch/arm/mm/dma-mapping.c

@@ -1775,10 +1775,8 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 	 * here, but instead have to make sure we only set but never clear it
 	 * for now.
 	 */
-	if (coherent) {
-		dev->archdata.dma_coherent = true;
+	if (coherent)
 		dev->dma_coherent = true;
-	}
 
 	/*
 	 * Don't override the dma_ops if they have already been set. Ideally