[PATCH] ramfs: update dir mtime and ctime

Phil Marek <philipp.marek@bmlv.gv.at> points out that ramfs forgets to update
a directory's mtime and ctime when it is modified.

Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>