bind_config: Fail if a known option couldn't be set

Make ssh_bind_options_parse_config() to fail if setting a known option
fails. Previously the return value of ssh_bind_options_set() were
ignored when configuring the server through a configuration file.

Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>