CPUArchState is no longer needed.

Prepares for changing qemu_kvm_init_cpu_signals() argument to CPUState.
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAndreas Färber <afaerber@suse.de>