KVM: VMX: Move common fields of struct vcpu_{vmx,tdx} to a struct

Move common fields of struct vcpu_vmx and struct vcpu_tdx to struct
vcpu_vt, to share the code between VMX/TDX as much as possible and to make
TDX exit handling more VMX like.

No functional change intended.

[Adrian: move code that depends on struct vcpu_vmx back to vmx.h]

Suggested-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/Z1suNzg2Or743a7e@google.com


Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Message-ID: <20250129095902.16391-5-adrian.hunter@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>