sh: make use of for_each_node_by_type()

Instead of open-coding the loop, let's use canned macro.

Also make sure we are not leaking "cpus" node reference.

Link: http://lkml.kernel.org/r/20180624224252.GA220395@dtor-ws


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>