KVM: VMX: Shadow VMCS secondary execution controls

Prepare to shadow all major control fields on a per-VMCS basis, which
allows KVM to avoid costly VMWRITEs when switching between vmcs01 and
vmcs02.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>