SUNRPC: remove rpcbind clients destruction on module cleanup

Rpcbind clients destruction during SUNRPC module removing is obsolete since now
those clients are destroying during last RPC service shutdown.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>