iommu/arm-smmu-v3: Make BTM optional for SVA

When BTM isn't supported by the SMMU, send invalidations on the
command queue.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20210122151054.2833521-3-jean-philippe@linaro.org


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