cnic: Use proper ulp_ops for per device operations.

For per device operations, cnic needs to dereference the RCU protected
cp->ulp_ops instead of the global cnic_ulp_tbl.  In 2 locations,
cnic_send_nlmsg() and cnic_copy_ulp_stats(), it was referencing the
global table.  If the device has been unregistered and these functions
are still being called (very unlikely scenarios), it could lead to NULL
pointer dereference.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>