kvm: x86: Introduce APICv x86 ops for checking APIC inhibit reasons

Inibit reason bits are used to determine if APICv deactivation is
applicable for a particular hardware virtualization architecture.

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>