The ovmf_suffix.bin contains the last 4KB of the OVMF.fd binary from edk2's
OvmfPkg/AmdSev/AmdSevX64.dsc build. To save space, we committed only the
last 4KB instead of the the full 4MB binary.
The end of the file contains a GUIDed footer table with entries that hold the SEV-ES AP reset vector address, which is needed in order to compute VMSAs for SEV-ES guests.