iommu: Remove unused IOMMU_SYS_CACHE_ONLY flag

The IOMMU_SYS_CACHE_ONLY flag was never exposed via the DMA API and
has no in-tree users. Remove it.

Cc: Robin Murphy <robin.murphy@arm.com>
Cc: "Isaac J. Manjarres" <isaacm@codeaurora.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Rob Clark <robdclark@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Will Deacon <will@kernel.org>

drivers/iommu/io-pgtable-arm.c

@@ -438,9 +438,6 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable *data,
 		else if (prot & IOMMU_CACHE)
 			pte |= (ARM_LPAE_MAIR_ATTR_IDX_CACHE
 				<< ARM_LPAE_PTE_ATTRINDX_SHIFT);
-		else if (prot & IOMMU_SYS_CACHE_ONLY)
-			pte |= (ARM_LPAE_MAIR_ATTR_IDX_INC_OCACHE
-				<< ARM_LPAE_PTE_ATTRINDX_SHIFT);
 	}
 
 	if (prot & IOMMU_CACHE)

include/linux/iommu.h

@@ -31,12 +31,6 @@
  * if the IOMMU page table format is equivalent.
  */
 #define IOMMU_PRIV	(1 << 5)
-/*
- * Non-coherent masters can use this page protection flag to set cacheable
- * memory attributes for only a transparent outer level of cache, also known as
- * the last-level or system cache.
- */
-#define IOMMU_SYS_CACHE_ONLY	(1 << 6)
 
 struct iommu_ops;
 struct iommu_group;