openrisc: fix CONFIG_UID16 setting

openrisc: fix CONFIG_UID16 setting

openrisc-allnoconfig:

  kernel/uid16.c: In function 'SYSC_setgroups16':
  kernel/uid16.c:184:2: error: implicit declaration of function 'groups_alloc'
  kernel/uid16.c:184:13: warning: assignment makes pointer from integer without a cast

openrisc shouldn't be setting CONFIG_UID16 when CONFIG_MULTIUSER=n.

Fixes: 2813893f8b197a1 ("kernel: conditionally support non-root users, groups and capabilities")
Reported-by: Fengguang Wu <[email protected]>
Cc: Iulia Manda <[email protected]>
Cc: Josh Triplett <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>