fs/9p: kerneldoc fixes

Function parameters comment fixing.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>