tools: Fix knot_schema field references
tools: Fix knot_schema field references

Fixes the code according to the new field names introduced by the
following KNOT proto commits:
2c3ca41bad9a18b386e0083f7cfe438ab060d2e1
aecc89aca27f9136e8d39b88577ca212b2faddf6

CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source