KVM: arm64: Add sanitisation for FEAT_FGT2 registers

Just like the FEAT_FGT registers, treat the FGT2 variant the same
way. THis is a large  update, but a fairly mechanical one.

The config dependencies are extracted from the 2025-03 JSON drop.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>