Refactor: libcrmcommon: simplify update_validation() loop

Move the (!transform) test after the (current_schema->schema_index == max)
test. If the current schema is the maximum, then the next iteration will just
hit the (current_schema->schema_index > max) test and break anyway.

This allows us to combine the (!transform) and
(current_schema->transform == NULL) tests for simplicity.