rdma :mount fails for nfs protocol in rdma volumes

When we mount rdma only volume or tcp,rdma volume using newly
peer probed IP's(nfs-server on new nodes) through nfs protocol,
mount fails for rdma only volume and mount happens with
help of tcp protocol in the case of tcp,rdma volumes. That is for
newly added servers will always get transport type as "socket".
This is due to nfs_transport_type is exported correctly and
imported wrongly.

This can be verified by the following ,
   * Create a rdma only volume or tcp,rdma volume
   * Add a new server into the trusted pool.
   * Checkout the client transport type specified nfs-server
     volgraph.It will be always tcp(socket type) instead of rdma.
   * And also for rdma only volume in the nfs log, we can see
     'connection refused' message for every reconnect between
     nfs server and glusterfsd.

BUG: 1157381

Change-Id: I6bd4979e31adfc72af92c1da06a332557b6289e2
Author:    Jiffin Tony Thottan <jthottan@redhat.com>
Signed-off-by: Jiffin Tony Thottan <jthottan@redhat.com>
Reviewed-on: http://review.gluster.org/8975
Reviewed-by: Meghana M <mmadhusu@redhat.com>
Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>
Tested-by: Niels de Vos <ndevos@redhat.com>