Revert "local_t Documentation update"

This reverts commit e1265205.

It's a duplicate commit of commit 74beb9db,
resulting in a duplicate section.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>