RDMA/cma: Add IPv6 support for iWARP

Modify the type of local_addr and remote_addr fields in struct
iw_cm_id from struct sockaddr_in to struct sockaddr_storage to hold
IPv6 and IPv4 addresses uniformly.

Change the references of local_addr and remote_addr in cxgb4, cxgb3,
nes and amso drivers to match this.  However to be able to actully run
traffic over IPv6, low-level drivers have to add code to support this.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Reviewed-by: Sean Hefty <sean.hefty@intel.com>

[ Fix unused variable warnings when INFINIBAND_NES_DEBUG not set.
  - Roland ]

Signed-off-by: Roland Dreier <roland@purestorage.com>