KVM x86 APIC changes for 6.3:
- Remove a superfluous variables from apic_get_tmcct()
- Fix various edge cases in x2APIC MSR emulation
- Mark APIC timer as expired if its in one-shot mode and the count
underflows while the vCPU task was being migrated
- Reset xAPIC when userspace forces "impossible" x2APIC => xAPIC transition