iommu/arm-smmu: add support for IOMMU_EXEC

Previously, all of our mappings were marked as executable, which isn't
usually required. Now that we have the IOMMU_EXEC flag, use that to
determine whether or not a mapping should be marked as executable.

Change-Id: Id5f9d5c75eedd48f90f508f57b633681cfc5a93d
Signed-off-by: Will Deacon <will.deacon@arm.com>
Git-commit: cf2d45b19ddb361241f36d8c9f3d0b234a18459b
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>