SUNRPC: Kill RPC_DISPLAY_ALL

At some point, I recall that rpc_pipe_fs used RPC_DISPLAY_ALL.
Currently there are no uses of RPC_DISPLAY_ALL outside the transport
modules themselves, so we can safely get rid of it.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>