arm64/sve: Make sysctl interface for SVE reusable by SME

arm64/sve: Make sysctl interface for SVE reusable by SME

The vector length configuration for SME is very similar to that for SVE
so in order to allow reuse refactor the SVE configuration so that it takes
the vector type from the struct ctl_table. Since there's no dedicated space
for this we repurpose the extra1 field to store the vector type, this is
otherwise unused for integer sysctls.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211210184133.320748-2-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>