char, another tmp_buf cleanup

No need to allocate one page as a side buffer.  It's no more used.  Clean this
(de)allocs of this useless memory pages in char subtree.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>