Support for enforced STOPs will allow us to use SCCB compatible devices.

Based on a preliminary patch by Wolfram Sang.
Signed-off-by: NJean Delvare <jdelvare@suse.de>
Tested-by: NWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>