ipc/util.c: use __seq_open_private() instead of seq_open()

ipc/util.c: use __seq_open_private() instead of seq_open()

Using __seq_open_private() removes boilerplate code from
sysvipc_proc_open().

The resultant code is shorter and easier to follow.

However, please note that __seq_open_private() call kzalloc() rather than
kmalloc() which may affect timing due to the memory initialisation
overhead.

Signed-off-by: Rob Jones <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>