Move the kvm_x86_ops functions that are used only within the scope of
kvm_init() into a separate struct, kvm_x86_init_ops.  In addition to
identifying the init-only functions without restorting to code comments,
this also sets the stage for waiting until after ->hardware_setup() to
set kvm_x86_ops.  Setting kvm_x86_ops after ->hardware_setup() is
desirable as many of the hooks are not usable until ->hardware_setup()
completes.

No functional change intended.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200321202603.19355-3-sean.j.christopherson@intel.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>