NFS/pNFS: Set the connect timeout for the pNFS flexfiles driver

Ensure that the connect timeout for the pNFS flexfiles driver is of the
same order as the I/O timeout, so that we can fail over quickly when
trying to read from a data server that is down.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>