s390/uaccess: remove dead kernel parameter 'user_mode='

Remove another leftover from the time when we supported running
user space in either home or primary address space.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
1 file changed