KVM: arm/arm64: Move phys_timer_emulate function

We are about to call phys_timer_emulate() from kvm_timer_update_state()
and modify phys_timer_emulate() at the same time.  Moving the function
and modifying it in a single patch makes the diff hard to read, so do
this separately first.

No functional change.

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