nfsv4.1: resulting notification bitmap should match requests length

Though bitmap can have an arbitrary length, the linux 5.10 client expects
device notification bitmap to be size of one (1).

Update OperationGETDEVICEINFO to initialize resulting notification bitmap
with the length that matches requested notification bitmap.

Linux 5.10 client processes the result of getdeviceinfo operation as expected.

Target: 0.22, master
Acked-by: Paul Millar
Acked-by: Albert Rossi
1 job for master in 1 minute and 10 seconds (queued for 25 seconds)