ixgbe: Remove an obsolete comment about ITR

The InterruptThrottleRate has been removed from ixgbe. Then Update
the comment.
Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -2529,8 +2529,6 @@ static void ixgbe_configure_msix(struct ixgbe_adapter *adapter)
  *      based on theoretical maximum wire speed and thresholds were set based
  *      on testing data as well as attempting to minimize response time
  *      while increasing bulk throughput.
- *      this functionality is controlled by the InterruptThrottleRate module
- *      parameter (see ixgbe_param.c)
  **/
 static void ixgbe_update_itr(struct ixgbe_q_vector *q_vector,
 			     struct ixgbe_ring_container *ring_container)