arm64: cpufeature: Export symbol read_sanitised_ftr_reg()

arm64: cpufeature: Export symbol read_sanitised_ftr_reg()

The SMMUv3 driver would like to read the MMFR0 PARANGE field in order to
share CPU page tables with devices. Allow the driver to be built as
module by exporting the read_sanitized_ftr_reg() cpufeature symbol.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20200918101852.582559-7-jean-philippe@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>