KVM: arm64: use common invariant sysreg definitions

Now that we have common definitions for the register encodings used by
KVM, make the KVM code uses thse for invariant sysreg definitions. This
makes said definitions a reasonable amount shorter, especially as many
comments are rendered redundant and can be removed.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: kvmarm@lists.cs.columbia.edu