kernel/hung_task.c: change hung_task.c to use for_each_process_thread()

kernel/hung_task.c: change hung_task.c to use for_each_process_thread()

In check_hung_uninterruptible_tasks() avoid the use of deprecated
while_each_thread().

The "max_count" logic will prevent a livelock - see commit 0c740d0a
("introduce for_each_thread() to replace the buggy while_each_thread()").
Having said this let's use for_each_process_thread().

Signed-off-by: Aaron Tomlin <[email protected]>
Acked-by: Oleg Nesterov <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dave Wysochanski <[email protected]>
Cc: Aaron Tomlin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>