Fix recent change to kdcdefaults processing

When falling back to reading kdc_tcp_ports from [kdcdefaults], assign
the result to the correct variable.

https://github.com/krb5/krb5/commit/5eb0d447050c688b1003ad7d5cd0e2e733187298
Author: Greg Hudson <ghudson@mit.edu>
Commit: 5eb0d447050c688b1003ad7d5cd0e2e733187298
Branch: master
 src/kdc/main.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)