Add PTP IEEE-1588 support and make it accessible via PHC subsystem.
The functionality is enabled for T5/T6 adapters. Driver interfaces with
Firmware to program and adjust the clock offset.

Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: NAtul Gupta <atul.gupta@chelsio.com>
Signed-off-by: NGanesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>