iommu/arm-smmu: change IOMMU_EXEC to IOMMU_NOEXEC

Exposing the XN flag of the SMMU driver as IOMMU_NOEXEC instead of
IOMMU_EXEC makes it enforceable, since for IOMMUs that don't support
the XN flag pages will always be executable.

Change-Id: Ib785acd8a188fa95aea9991116139a392862764e
Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Git-commit: a720b41c41f5a7e4c51558cf087882c57331581f
[rvaswani@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>