iommu: add capability IOMMU_CAP_NOEXEC

Some IOMMUs accept an IOMMU_NOEXEC protection flag in addition to
IOMMU_READ and IOMMU_WRITE. Expose this as an IOMMU capability.
Signed-off-by: NAntonios Motakis <a.motakis@virtualopensystems.com>
Acked-by: NJoerg Roedel <jroedel@suse.de>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

include/linux/iommu.h

@@ -61,6 +61,7 @@ enum iommu_cap {
 	IOMMU_CAP_CACHE_COHERENCY,	/* IOMMU can enforce cache coherent DMA
 					   transactions */
 	IOMMU_CAP_INTR_REMAP,		/* IOMMU supports interrupt isolation */
+	IOMMU_CAP_NOEXEC,		/* IOMMU_NOEXEC flag */
 };
 
 /*