cifs: Don't display RDMA transport on reconnect

commit 14cc639c upstream.

On reconnect, the transport data structure is NULL and its information is not
available.

Signed-off-by: Long Li <longli@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>