net: aquantia: PTP skeleton declarations and callbacks

Here we add basic function for PTP clock register/unregister.
We also declare FW/HW capability bits used to control PTP feature on device.

PTP device is created if network card has appropriate FW that has PTP
enabled in config. HW supports timestamping for PTPv2 802.AS1 and
PTPv2 IPv4 UDP packets.

It also supports basic PTP callbacks for getting/setting time, adjusting
frequency and time as well.

Signed-off-by: Egor Pomozov <epomozov@marvell.com>
Co-developed-by: Sergey Samoilenko <sergey.samoilenko@aquantia.com>
Signed-off-by: Sergey Samoilenko <sergey.samoilenko@aquantia.com>
Co-developed-by: Dmitry Bezrukov <dmitry.bezrukov@aquantia.com>
Signed-off-by: Dmitry Bezrukov <dmitry.bezrukov@aquantia.com>
Signed-off-by: Igor Russkikh <igor.russkikh@aquantia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>