bnxt_en: Enable packet timestamping for all RX packets

Add driver support to enable timestamping on all RX packets
that are received by the NIC. This capability can be requested
by the applications using SIOCSHWTSTAMP ioctl with filter type
HWTSTAMP_FILTER_ALL.

Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>