NFS: fix typo in parameter description

Fix typo in parameter description.

Fixes: 5405fc44 ("NFSv4.x: Add kernel parameter to control the
callback server")
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/super.c

@@ -2904,7 +2904,7 @@ module_param(max_session_slots, ushort, 0644);
 MODULE_PARM_DESC(max_session_slots, "Maximum number of outstanding NFSv4.1 "
 		"requests the client will negotiate");
 module_param(max_session_cb_slots, ushort, 0644);
-MODULE_PARM_DESC(max_session_slots, "Maximum number of parallel NFSv4.1 "
+MODULE_PARM_DESC(max_session_cb_slots, "Maximum number of parallel NFSv4.1 "
 		"callbacks the client will process for a given server");
 module_param(send_implementation_id, ushort, 0644);
 MODULE_PARM_DESC(send_implementation_id,