arm: Remove dev->archdata.iommu pointer

There are no users left, all drivers have been converted to use the
per-device private pointer offered by IOMMU core.

Signed-off-by: Joerg Roedel <[e-mail]>
Reviewed-by: Jerry Snitselaar <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/arm/include/asm/device.h

···
 #ifdef CONFIG_DMABOUNCE
 	struct dmabounce_device_info *dmabounce;
 #endif
-#ifdef CONFIG_IOMMU_API
-	void *iommu; /* private IOMMU data */
-#endif
 #ifdef CONFIG_ARM_DMA_USE_IOMMU
 	struct dma_iommu_mapping	*mapping;
 #endif