bnxt_en: Add BCM5760X specific PHC registers mapping

BCM5760X firmware will advertise direct 64-bit PHC registers access
for the driver from BAR0.

Make the necessary changes in handling HWRM_PORT_MAC_PTP_QCFG's
response and PHC register mapping for 5760X chips.

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>