i386/tdx: Add TDVF memory via KVM_TDX_INIT_MEM_REGION

i386/tdx: Add TDVF memory via KVM_TDX_INIT_MEM_REGION

TDVF firmware (CODE and VARS) needs to be copied to TD's private
memory via KVM_TDX_INIT_MEM_REGION, as well as TD HOB and TEMP memory.

If the TDVF section has TDVF_SECTION_ATTRIBUTES_MR_EXTEND set in the
flag, calling KVM_TDX_EXTEND_MEMORY to extend the measurement.

After populating the TDVF memory, the original image located in shared
ramblock can be discarded.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250508150002.689633-25-xiaoyao.li@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>