net: usb/phy: asix: add support for ax88772A/C PHYs

Add support for build-in x88772A/C PHYs

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>