9p: kerneldoc warning fixes

options argument was removed from v9fs_session_info in commit 4b53e4b5
("9p: remove unnecessary v9fses->options which duplicates the mount string")

iov and nr_segs were removed from v9fs_direct_IO
in commit d8d3d94b
("pass iov_iter to ->direct_IO()")

Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Cc: v9fs-developer@lists.sourceforge.net
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>