According to our parser (virDomainTPMDefParseXML()) the version
is an optional attribute and independent of TPM backend type.
Therefore, it's not a choice group, which is what our RNG schema
suggests.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>