iommu/arm-smmu: Expose s2cr and smr structs to impl

Move the arm_smmu_s2cr and arm_smmu_smr structs to the internal header
file, in order to expose them to the platform specific arm-smmu
implementations.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20191226221709.3844244-3-bjorn.andersson@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>