bnxt_en: 1PPS support for 5750X family chips

1PPS (One Pulse Per Second) is a signal generated either
by the NIC PHC or an external timing source.
Integrating the support to configure and use 1PPS using
the TSIO pins along with PTP timestamps will add Grand
Master capability to the 5750X family chipsets.

This patch initializes the driver data structures and
registers the 1PPS with kernel, based on the TSIO pins'
capability in the hardware. This will create a /dev/ppsX
device which applications can use to receive PPS events.

Later patches will define functions to configure and use
the pins.

Reviewed-by: Edwin Peer <edwin.peer@broadcom.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>