i386/tdx: Fetch and validate CPUID of TD guest

i386/tdx: Fetch and validate CPUID of TD guest

Use KVM_TDX_GET_CPUID to get the CPUIDs that are managed and enfored
by TDX module for TD guest. Check QEMU's configuration against the
fetched data.

Print wanring  message when 1. a feature is not supported but requested
by QEMU or 2. QEMU doesn't want to expose a feature while it is enforced
enabled.

- If cpu->enforced_cpuid is not set, prints the warning message of both
1) and 2) and tweak QEMU's configuration.

- If cpu->enforced_cpuid is set, quit if any case of 1) or 2).

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20250508150002.689633-52-xiaoyao.li@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>