arm64/sve: Make sve_state_size() static

There are no users outside fpsimd.c so make sve_state_size() static.
KVM open codes an equivalent.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211019172247.3045838-4-broonie@kernel.org


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