iommu/arm-smmu: provide option to dsb macro when publishing tables

On coherent systems, publishing new page tables to the SMMU walker is
achieved with a dsb instruction. In fact, this can be a dsb(ishst) which
also provides the mandatory barrier option for arm64.

Change-Id: I511732013179e363b212239b92c484f10b96e2df
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Git-commit: 3aa80ea4c90d46ffbe200d05b9ceb997001b36df
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


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