chsmack: better naming
chsmack: better naming

The name 'option_flag' wasn't very good.
The new name 'modify' is more explicit.

Signed-off-by: José Bollo <08496fd66cc394b517cafa0b18bcb9ce79fe4230@iot.bzh>

jobol/smack,jobol/smack,smack-team/smack,smack-team/smack