selftests: arm64: Verify interoperation of SVE and FPSIMD register sets

After setting the FPSIMD registers via the SVE register set read them back
via the FPSIMD register set, validating that the two register sets are
interoperating and that the values we thought we set made it into the
child process.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210913125505.52619-7-broonie@kernel.org


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