krb5_get_name_canon_rules: fix profile location

[realms] <realm> { name_canon_rules = <strings> }

not

[libdefaults] <realm> { name_canon_rules = <strings> }

Change-Id: I770c2250333d2649f983f015de94f30740c9771d
(cherry picked from commit c07aaee1287b0059376da4aac0e7417d992faed7)