Fetching PTP sync information from mailbox is slow and can take
up to 10 milliseconds. Reduce this unnecessary delay by directly
reading the information from the corresponding registers.

Fixes: 9c33e420 ("cxgb4: Add PTP Hardware Clock (PHC) support")
Signed-off-by: Manoj Malviya <manojmalviya@chelsio.com>
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>