sched: don't forget to unlock uids_mutex on error paths

sched: don't forget to unlock uids_mutex on error paths

The commit

 commit 5cb350baf580017da38199625b7365b1763d7180
 Author: Dhaval Giani <[email protected]>
 Date:   Mon Oct 15 17:00:14 2007 +0200

    sched: group scheduling, sysfs tunables

introduced the uids_mutex and the helpers to lock/unlock it.
Unfortunately, the error paths of alloc_uid() were not patched
to unlock it.

Signed-off-by: Pavel Emelyanov <[email protected]>
Acked-by: Dhaval Giani <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>