Add support for the CB.ProbeUuid cache manager RPC op.  This allows a modern
OpenAFS server to quickly ask if the client has been rebooted.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>