Now that indexing into arch.regs is either protected by WARN_ON_ONCE or
done with hardcoded enums, combine all definitions for registers that
are tracked by regs_avail and regs_dirty into 'enum kvm_reg'.  Having a
single enum type will simplify additional cleanup related to regs_avail
and regs_dirty.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>