KVM: lapic: Use guest_cpuid_has() in kvm_apic_set_version()

Only code cleanup and no functional change.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200708065054.19713-8-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>