Switched cpuset_common_file_read() to simple_read_from_buffer(), killed
a bunch of useless (and not quite correct - e.g.  min(size_t,ssize_t))
code.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>