Fix typos in kdb5_util master key command outputs

kdb5_util list_mkeys was beginning lines with "KNVO" instead of
"KVNO".  kdb5_util purge_mkeys was displaying "follwing" instead of
"following" for both dry-run and normal cases.

(cherry picked from commit 7fee58ccadf1b61eec9a8c62f47dac43986e2ad1)

https://github.com/krb5/krb5/commit/00dd6cb24a1e35475b55587214359fd9f4718e80
Author: Greg Hudson <ghudson@mit.edu>
Committer: Tom Yu <tlyu@mit.edu>
Commit: 00dd6cb24a1e35475b55587214359fd9f4718e80
Branch: krb5-1.12
 src/kadmin/dbutil/kdb5_mkey.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)