Group the code this way so that we can avoid too many ifdef's:
Data only used in an SNP VM with the paravisor;
Functions only used in an SNP VM with the paravisor;
Data only used in an SNP VM without the paravisor;
Functions only used in an SNP VM without the paravisor;
Functions only used in a TDX VM, with and without the paravisor;
Functions used in an SNP or TDX VM, when the paravisor is present;
Functions always used, even in a regular non-CoCo VM.
No functional change.
Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>