NFS: fix typo in parameter description

Fix typo in parameter description.

Fixes: 5405fc44c337 ("NFSv4.x: Add kernel parameter to control the
callback server")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
1 file changed