cxgbe(4): Link related changes.

cxgbe(4): Link related changes.

- Switch to using 32b port/link capabilities in the driver.  The 32b
  format is used internally by firmwares > 1.16.45.0 and the driver will
  now interact with the firmware in its native format, whether it's 16b
  or 32b.  Note that the 16b format doesn't have room for 50G, 200G, or
  400G speeds.

- Add a bit in the pause_settings knobs to allow negotiated PAUSE
  settings to override manual settings.

- Ensure that manual link settings persist across an administrative
  down/up as well as transceiver unplug/replug.

- Remove unused is_*G_port() functions.

Approved by:	re@ (gjb@)
MFC after:	1 month
Sponsored by:	Chelsio Communications