SUNRPC: Don't auto-disconnect from the local rpcbind socket

commit 00326ed6442c66021cd4b5e19e80f3e2027d5d42 upstream.

There is no need for the kernel to time out the AF_LOCAL connection to
the rpcbind socket, and doing so is problematic because when it is
time to reconnect, our process may no longer be using the same mount
namespace.

Reported-by: Nix <nix@esperi.org.uk>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>