bld_ifw_tools: Remove the --license argument and its usage

The --license argument is never used, so removing it.
Also, remove it from create_installer.py when using IfwOptions

Change-Id: Ie87628798a3cdd96970362f2ead375a4d156d31a
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>