arm64: KVM: Move kvm_vcpu_get_condition out of emulate.c

In order to make emulate.c more generic, move the arch-specific
manupulation bits out of emulate.c.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>