GPO: ignore non-KVP lines if possible
    
    Ticket:
    https://fedorahosted.org/sssd/ticket/2751
    
    Non-KVP break GPO processing. They are
    used for values we are not interested in
    so it is safe to ignore them.
    
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>