iommu/arm-smmu-v3: Split arm_smmu_tlb_inv_range()

Extract some of the cmd initialization and the ATC invalidation from
arm_smmu_tlb_inv_range(), to allow an MMU notifier to invalidate a VA
range by ASID.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20210122151054.2833521-2-jean-philippe@linaro.org


Signed-off-by: Will Deacon <will@kernel.org>