[PATCH] v9fs: add extension field to Tcreate

Implement a new way of creating special files.  Instead of Tcreate+Twstat,
add one more field to Tcreate that contains special file description.

Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>