SUNRPC: pass buffer size to svc_sock_names()

Adjust the synopsis of svc_sock_names() to pass in the size of the
output buffer.  Add a documenting comment.

This is a cosmetic change for now.  A subsequent patch will make sure
the buffer length is passed to one_sock_name(), where the length will
actually be useful.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 1f1c215..b64a7fb 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -966,7 +966,8 @@
 		return -ENOMEM;
 
 	if (nfsd_serv != NULL)
-		len = svc_sock_names(buf, nfsd_serv, toclose);
+		len = svc_sock_names(nfsd_serv, buf,
+					SIMPLE_TRANSACTION_LIMIT, toclose);
 	if (len >= 0)
 		lockd_down();