ipa_kdb: Fix memory leak
    
    ipadb_get_principal() allocates client_actual. Call
    ipadb_free_principal to release it.
    
    Rather than spreading the free() amongst the code introduce
    done as a target to match behavior in similar functions.
    
    Discovered by coverity.
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Robbie Harwood <rharwood@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>